Inestrosa NC

General

Full name : Inestrosa Nibaldo C

First name : Nibaldo C

Mail : Catholic University of Chile, Dept of Cell & Molecular Biology, Faculty of Biological Sciences, Alameda 340, Santiago

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Country : Chile

Email : ninestrosa@bio.puc.cl

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References (162)

Title : Discovery of a Potent Dual Inhibitor of Acetylcholinesterase and Butyrylcholinesterase with Antioxidant Activity that Alleviates Alzheimer-like Pathology in Old APP\/PS1 Mice - Viayna_2021_J.Med.Chem_64_812
Author(s) : Viayna E , Coquelle N , Cieslikiewicz-Bouet M , Cisternas P , Oliva CA , Sanchez-Lopez E , Ettcheto M , Bartolini M , De Simone A , Ricchini M , Rendina M , Pons M , Firuzi O , Perez B , Saso L , Andrisano V , Nachon F , Brazzolotto X , Garcia ML , Camins A , Silman I , Jean L , Inestrosa NC , Colletier JP , Renard PY , Munoz-Torrero D
Ref : Journal of Medicinal Chemistry , 64 :812 , 2021
Abstract : The combination of the scaffolds of the cholinesterase inhibitor huprine Y and the antioxidant capsaicin results in compounds with nanomolar potencies toward human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) that retain or improve the antioxidant properties of capsaicin. Crystal structures of their complexes with AChE and BChE revealed the molecular basis for their high potency. Brain penetration was confirmed by biodistribution studies in C57BL6 mice, with one compound (5i) displaying better brain/plasma ratio than donepezil. Chronic treatment of 10 month-old APP/PS1 mice with 5i (2 mg/kg, i.p., 3 times per week, 4 weeks) rescued learning and memory impairments, as measured by three different behavioral tests, delayed the Alzheimer-like pathology progression, as suggested by a significantly reduced Abeta42/Abeta40 ratio in the hippocampus, improved basal synaptic efficacy, and significantly reduced hippocampal oxidative stress and neuroinflammation. Compound 5i emerges as an interesting anti-Alzheimer lead with beneficial effects on cognitive symptoms and on some underlying disease mechanisms.
ESTHER : Viayna_2021_J.Med.Chem_64_812
PubMedSearch : Viayna_2021_J.Med.Chem_64_812
PubMedID: 33356266
Gene_locus related to this paper: human-ACHE

Title : Huperzine A and Its Neuroprotective Molecular Signaling in Alzheimer's Disease - Friedli_2021_Molecules_26_
Author(s) : Friedli MJ , Inestrosa NC
Ref : Molecules , 26 : , 2021
Abstract : Huperzine A (HupA), an alkaloid found in the club moss Huperzia serrata, has been used for centuries in Chinese folk medicine to treat dementia. The effects of this alkaloid have been attributed to its ability to inhibit the cholinergic enzyme acetylcholinesterase (AChE), acting as an acetylcholinesterase inhibitor (AChEI). The biological functions of HupA have been studied both in vitro and in vivo, and its role in neuroprotection appears to be a good therapeutic candidate for Alzheimers disease (AD). Here, we summarize the neuroprotective effects of HupA on AD, with an emphasis on its interactions with different molecular signaling avenues, such as the Wnt signaling, the pre- and post-synaptic region mechanisms (synaptotagmin, neuroligins), the amyloid precursor protein (APP) processing, the amyloid-beta peptide (Abeta) accumulation, and mitochondrial protection. Our goal is to provide an integrated overview of the molecular mechanisms through which HupA affects AD.
ESTHER : Friedli_2021_Molecules_26_
PubMedSearch : Friedli_2021_Molecules_26_
PubMedID: 34770940

Title : Modulating Wnt signaling at the root: Porcupine and Wnt acylation - Torres_2019_Pharmacol.Ther_198_34
Author(s) : Torres VI , Godoy JA , Inestrosa NC
Ref : Pharmacol Ther , 198 :34 , 2019
Abstract : Communication between cells occurs through secreted molecules, among which Wnt ligands play a critical role in balancing cell proliferation, differentiation and cellular homeostasis. The action of Wnt signaling can be modulated at several levels, including posttranslational modification of the Wnt ligands, whose acylation is critical for biological activity. At least three enzymes are necessary for Wnt acylation/deacylation: stearoyl CoA desaturase (SCD), porcupine (PORCN) and Notum. At the endoplasmic reticulum (ER), SCD provides the monounsaturated fatty acid to PORCN, which adds it to the Wnt ligand; at the extracellular matrix, the fatty acid is removed by Notum. Obviously, the interplay between these enzymes will define Wnt signaling ligand secretion and activity. Excessive activation of Wnt signaling has been observed in a variety of solid tumors, which has led the pharmaceutical industry to develop specific inhibitors for this pathway that mainly target PORCN, some of which are in early clinical trials. In the central nervous system (CNS), Wnt signaling activation has been shown to have a neuroprotective effect, and conversely, its inhibition induces neurodegeneration, which implies that the inhibition of PORCN in cancer therapies should be used with caution, and the cognitive performance of the patient should be monitored during treatment. This review collects information about the PORCN enzyme in relation to its role in the Wnt pathway through the acylation of Wnt ligands, its inhibition by drugs in the treatment of some cancers, and its putative modulation in the treatment of neurodegenerative diseases.
ESTHER : Torres_2019_Pharmacol.Ther_198_34
PubMedSearch : Torres_2019_Pharmacol.Ther_198_34
PubMedID: 30790642

Title : Rhein-Huprine Derivatives Reduce Cognitive Impairment, Synaptic Failure and Amyloid Pathology in AbetaPPswe\/PS-1 Mice of Different Ages - Serrano_2016_Curr.Alzheimer.Res_13_1017
Author(s) : Serrano FG , Tapia-Rojas C , Carvajal FJ , Cisternas P , Viayna E , Sola I , Munoz-Torrero D , Inestrosa NC
Ref : Curr Alzheimer Res , 13 :1017 , 2016
Abstract : Alzheimer's disease (AD) is a neurodegenerative disorder in which the amyloid-beta (Abeta) peptide plays a key role in synaptic impairment and memory decline associated with neuronal dysfunction and intra-neuronal accumulation of hyperphosphorylated tau protein. Two novel enantiopure rhein-huprine hybrids ((+)-1 and (-)-1) exhibit potent inhibitory effects against human acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), BACE-1 and both Abeta and tau antiaggregation activity in vitro and reduction on the amyloid precursor protein (APP) processing in vivo. Interestingly, in this work, we observed beneficial effects with both (+)- and (-)-1 in the reversion of the neuropathology presented in the AbetaPPswe/PS-1 Alzheimer s model, including a reduction in the Abeta levels, tau phosphorylation and memory impairment with both treatments. Also, in young transgenic mice that present early symptoms of synaptic failure and memory loss, we found a protection of cognitive functions, including long-term potentiation (LTP) and a reduction of the neuro-inflammation by both (+)- and (-)-1. Furthermore, animals with an advanced disease (11month-old) present an exacerbate neurodegeneration that is reversed only with the dextrorotatory enantiomer. These studies indicated that rhein-huprine derivatives with multiple properties might have interesting therapeutic potential for AD.
ESTHER : Serrano_2016_Curr.Alzheimer.Res_13_1017
PubMedSearch : Serrano_2016_Curr.Alzheimer.Res_13_1017
PubMedID: 26502813

Title : The soluble extracellular fragment of neuroligin-1 targets Abeta oligomers to the postsynaptic region of excitatory synapses - Dinamarca_2015_Biochem.Biophys.Res.Commun_466_66
Author(s) : Dinamarca MC , Di Luca M , Godoy JA , Inestrosa NC
Ref : Biochemical & Biophysical Research Communications , 466 :66 , 2015
Abstract : Amyloid-beta oligomers (Abetao) play a major role in the synaptic dysfunction of Alzheimer's disease (AD). Neuroligins are postsynaptic cell-adhesion molecules, that share an extracellular domain with high degree of similarity to acetylcholinesterase (AChE), one of the first putative Abetao receptors. We recently found that Abetao interact with the soluble N-terminal fragment of neuroligin-1 (NL-1). We report here that Abetao associate with NL-1 at excitatory hippocampal synapses, whereas almost no association was observed with neuroligin-2, an isoform present at inhibitory synapses. Studies using purified hippocampal postsynaptic densities indicate that NL-1 interacts with Abetao in a complex with GluN2B-containing NMDA receptors. Additionally, the soluble fragment of NL-1 was used as a scavenger for Abetao. Field excitatory postsynaptic potentials indicate that fragments of NL-1 protect hippocampal neurons from the impairment induced by Abetao. To our knowledge, this is the first report of the interaction between this extracellular fragment of NL-1 and Abetao, strongly suggest that NL-1 facilitates the targeting of Abetao to the postsynaptic regions of excitatory synapses.
ESTHER : Dinamarca_2015_Biochem.Biophys.Res.Commun_466_66
PubMedSearch : Dinamarca_2015_Biochem.Biophys.Res.Commun_466_66
PubMedID: 26325471

Title : Synthesis and multitarget biological profiling of a novel family of rhein derivatives as disease-modifying anti-Alzheimer agents - Viayna_2014_J.Med.Chem_57_2549
Author(s) : Viayna E , Sola I , Bartolini M , De Simone A , Tapia-Rojas C , Serrano FG , Sabate R , Juarez-Jimenez J , Perez B , Luque FJ , Andrisano V , Clos MV , Inestrosa NC , Munoz-Torrero D
Ref : Journal of Medicinal Chemistry , 57 :2549 , 2014
Abstract : We have synthesized a family of rhein-huprine hybrids to hit several key targets for Alzheimer's disease. Biological screening performed in vitro and in Escherichia coli cells has shown that these hybrids exhibit potent inhibitory activities against human acetylcholinesterase, butyrylcholinesterase, and BACE-1, dual Abeta42 and tau antiaggregating activity, and brain permeability. Ex vivo studies with the leads (+)- and (-)-7e in brain slices of C57bl6 mice have revealed that they efficiently protect against the Abeta-induced synaptic dysfunction, preventing the loss of synaptic proteins and/or have a positive effect on the induction of long-term potentiation. In vivo studies in APP-PS1 transgenic mice treated ip for 4 weeks with (+)- and (-)-7e have shown a central soluble Abeta lowering effect, accompanied by an increase in the levels of mature amyloid precursor protein (APP). Thus, (+)- and (-)-7e emerge as very promising disease-modifying anti-Alzheimer drug candidates.
ESTHER : Viayna_2014_J.Med.Chem_57_2549
PubMedSearch : Viayna_2014_J.Med.Chem_57_2549
PubMedID: 24568372

Title : Peroxisome proliferators reduce spatial memory impairment, synaptic failure, and neurodegeneration in brains of a double transgenic mice model of Alzheimer's disease - Inestrosa_2013_J.Alzheimers.Dis_33_941
Author(s) : Inestrosa NC , Carvajal FJ , Zolezzi JM , Tapia-Rojas C , Serrano F , Karmelic D , Toledo EM , Toro A , Toro J , Santos MJ
Ref : J Alzheimers Dis , 33 :941 , 2013
Abstract : Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, accumulation of the amyloid-beta peptide (Abeta), increase of oxidative stress, and synaptic alterations. The scavenging of reactive oxygen species through their matrix enzyme catalase is one of the most recognized functions of peroxisomes. The induction of peroxisome proliferation is attained through different mechanisms by a set of structurally diverse molecules called peroxisome proliferators. In the present work, a double transgenic mouse model of AD that co-expresses a mutant human amyloid-beta protein precursor (AbetaPPswe) and presenilin 1 without exon 9 (PS1dE9) was utilized in order to assess the effect of peroxisomal proliferation on Abeta neurotoxicity in vivo. Mice were tested for spatial memory and their brains analyzed by cytochemical, electrophysiological, and biochemical methods. We report here that peroxisomal proliferation significantly reduces (i) memory impairment, found in this model of AD; (ii) Abeta burden and plaque-associated acetylcholinesterase activity; (iii) neuroinflammation, measured by the extent of astrogliosis and microgliosis; and (iv) the decrease in postsynaptic proteins, while promoting synaptic plasticity in the form of long-term potentiation. We concluded that peroxisomal proliferation reduces various AD neuropathological markers and peroxisome proliferators may be considered as potential therapeutic agents against the disease.
ESTHER : Inestrosa_2013_J.Alzheimers.Dis_33_941
PubMedSearch : Inestrosa_2013_J.Alzheimers.Dis_33_941
PubMedID: 23109558

Title : Tetrahydrohyperforin increases adult hippocampal neurogenesis in wild-type and APPswe\/PS1DeltaE9 mice - Abbott_2013_J.Alzheimers.Dis_34_873
Author(s) : Abbott AC , Calderon Toledo C , Aranguiz FC , Inestrosa NC , Varela-Nallar L
Ref : J Alzheimers Dis , 34 :873 , 2013
Abstract : Tetrahydrohyperforin (IDN5706), a semi-synthetic derivative of hyperforin, has shown neuroprotective properties preventing the impairment of synaptic plasticity and cognitive decline in an in vivo model of Alzheimer's disease (AD). Considering the reported role of adult neurogenesis in the plasticity of the hippocampal network, we investigated whether IDN5706 affects adult neurogenesis and hippocampal function. In hippocampal progenitors cultured from adult rats, IDN5706 increased proliferation. Moreover, treatment with IDN5706 for 4 weeks increased cell proliferation in the subgranular zone (SGZ) of the hippocampus in 2 month-old wild-type mice in vivo. As determined by double labeling with BrdU and neuronal markers, IDN5706 treatment increased the number of immature neurons and newborn mature neurons in the adult dentate gyrus. In addition, IDN5706 treatment improved long-term memory in a hippocampal-dependent spatial memory task. Finally, IDN5706 treatment increased cell proliferation and neural commitment in the SGZ of the double transgenic APPswe/PS1DeltaE9 mouse model of AD. These results indicate that IDN5706 increases adult hippocampal neurogenesis and may have therapeutic value in neurological disorders in which adult neurogenesis is impaired.
ESTHER : Abbott_2013_J.Alzheimers.Dis_34_873
PubMedSearch : Abbott_2013_J.Alzheimers.Dis_34_873
PubMedID: 23302657

Title : Wnt signaling in the regulation of adult hippocampal neurogenesis - Varela-Nallar_2013_Front.Cell.Neurosci_7_100
Author(s) : Varela-Nallar L , Inestrosa NC
Ref : Front Cell Neurosci , 7 :100 , 2013
Abstract : In the adult brain new neurons are continuously generated mainly in two regions, the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) in the hippocampal dentate gyrus. In the SGZ, radial neural stem cells (NSCs) give rise to granule cells that integrate into the hippocampal circuitry and are relevant for the plasticity of the hippocampus. Loss of neurogenesis impairs learning and memory, suggesting that this process is important for adult hippocampal function. Adult neurogenesis is tightly regulated by multiple signaling pathways, including the canonical Wnt/beta-catenin pathway. This pathway plays important roles during the development of neuronal circuits and in the adult brain it modulates synaptic transmission and plasticity. Here, we review current knowledge on the regulation of adult hippocampal neurogenesis by the Wnt/beta-catenin signaling cascade and the potential mechanisms involved in this regulation. Also we discuss the evidence supporting that the canonical Wnt pathway is part of the signaling mechanisms involved in the regulation of neurogenesis in different physiological conditions. Finally, some unsolved questions regarding the Wnt-mediated regulation of neurogenesis are discussed.
ESTHER : Varela-Nallar_2013_Front.Cell.Neurosci_7_100
PubMedSearch : Varela-Nallar_2013_Front.Cell.Neurosci_7_100
PubMedID: 23805076

Title : Postsynaptic Receptors for Amyloid-beta Oligomers as Mediators of Neuronal Damage in Alzheimer's Disease - Dinamarca_2012_Front.Physiol_3_464
Author(s) : Dinamarca MC , Rios JA , Inestrosa NC
Ref : Front Physiol , 3 :464 , 2012
Abstract : The neurotoxic effect of amyloid-beta peptide (Abeta) over the central synapses has been described and is reflected in the decrease of some postsynaptic excitatory proteins, the alteration in the number and morphology of the dendritic spines, and a decrease in long-term potentiation. Many studies has been carried out to identify the putative Abeta receptors in neurons, and is still no clear why the Abeta oligomers only affect the excitatory synapses. Abeta oligomers bind to neurite and preferentially to the postsynaptic region, where the postsynaptic protein-95 (PSD-95) is present in the glutamatergic synapse, and interacts directly with the N-methyl-D-aspartate receptor (NMDAR) and neuroligin (NL). NL is a postsynaptic protein which binds to the presynaptic protein, neurexin to form a heterophilic adhesion complex, the disruption of this interaction affects the integrity of the synaptic contact. Structurally, NL has an extracellular domain homolog to acetylcholinesterase, the first synaptic protein that was found to interact with Abeta. In the present review we will document the interaction between Abeta and the extracellular domain of NL-1 at the excitatory synapse, as well as the interaction with other postsynaptic components, including the glutamatergic receptors (NMDA and mGluR5), the prion protein, the neurotrophin receptor, and the alpha7-nicotinic acetylcholine receptor. We conclude that several Abeta oligomers receptors exist at the excitatory synapse, which could be the responsible for the neurotoxic effect described for the Abeta oligomers. The characterization of the interaction between Abeta receptors and Abeta oligomers could help to understand the source of the neurologic damage observed in the brain of the Alzheimer's disease patients.
ESTHER : Dinamarca_2012_Front.Physiol_3_464
PubMedSearch : Dinamarca_2012_Front.Physiol_3_464
PubMedID: 23267328

Title : SIRT1 regulates dendritic development in hippocampal neurons - Codocedo_2012_PLoS.One_7_e47073
Author(s) : Codocedo JF , Allard C , Godoy JA , Varela-Nallar L , Inestrosa NC
Ref : PLoS ONE , 7 :e47073 , 2012
Abstract : Dendritic arborization is required for proper neuronal connectivity. SIRT1, a NAD+ dependent histone deacetylase, has been associated to ageing and longevity, which in neurons is linked to neuronal differentiation and neuroprotection. In the present study, the role of SIRT1 in dendritic development was evaluated in cultured hippocampal neurons which were transfected at 3 days in vitro with a construct coding for SIRT1 or for the dominant negative SIRT1H363Y, which lacks the catalytic activity. Neurons overexpressing SIRT1 showed an increased dendritic arborization, while neurons overexpressing SIRT1H363Y showed a reduction in dendritic arbor complexity. The effect of SIRT1 was mimicked by treatment with resveratrol, a well known activator of SIRT1, which has no effect in neurons overexpressing SIRT1H363Y indicating that the effect of resveratrol was specifically mediated by SIRT1. Moreover, hippocampal neurons overexpressing SIRT1 were resistant to dendritic dystrophy induced by Abeta aggregates, an effect that was dependent on the deacetylase activity of SIRT1. Our findings indicate that SIRT1 plays a role in the development and maintenance of dendritic branching in hippocampal neurons, and suggest that these effects are mediated by the ROCK signaling pathway.
ESTHER : Codocedo_2012_PLoS.One_7_e47073
PubMedSearch : Codocedo_2012_PLoS.One_7_e47073
PubMedID: 23056585

Title : Wnt-5a is a synaptogenic factor with neuroprotective properties against Abeta toxicity - Varela-Nallar_2012_Neurodegener.Dis_10_23
Author(s) : Varela-Nallar L , Parodi J , Farias GG , Inestrosa NC
Ref : Neurodegener Dis , 10 :23 , 2012
Abstract : BACKGROUND: We have recently found that Wnt-5a regulates the synaptic structure and function in hippocampal neurons. This ligand is expressed in the hippocampus, stimulates dendritic spine morphogenesis and increases glutamatergic neurotransmission. Moreover, we have also shown that Wnt-5a induces the clustering of PSD-95. OBJECTIVE: To explore the role of Wnt-5a in the formation of synaptic contacts.
METHODS: Primary rat hippocampal neurons were exposed to a formylated hexapeptide (Foxy-5) derived from the sequence of Wnt-5a to study synapse formation and function.
RESULTS: In short-term experiments, Wnt-5a only induced the clustering of PSD-95 but had no effect on the density of presynaptic puncta, while in long-term experiments, it induced both pre- and postsynaptic protein clustering and the number of synaptic contacts, in agreement with electrophysiological studies. In long-term experiments, Foxy-5 increased miniature excitatory postsynaptic current amplitude and frequency. CONCLUSION: Our findings indicate that Wnt-5a induces synapse formation in hippocampal neurons. In addition, we discuss recent findings indicating a neuroprotective action of Wnt-5a against Abeta neurotoxicity.
ESTHER : Varela-Nallar_2012_Neurodegener.Dis_10_23
PubMedSearch : Varela-Nallar_2012_Neurodegener.Dis_10_23
PubMedID: 22261402

Title : Frizzled receptors in neurons: from growth cones to the synapse - Varela-Nallar_2012_Cytoskeleton.(Hoboken)_69_528
Author(s) : Varela-Nallar L , Ramirez VT , Gonzalez-Billault C , Inestrosa NC
Ref : Cytoskeleton (Hoboken) , 69 :528 , 2012
Abstract : The Wnt signaling pathway has been implicated in several different aspects of neural development and function, including dendrite morphogenesis, axonal growth and guidance, synaptogenesis and synaptic plasticity. Here, we studied several Frizzled Wnt receptors and determined their differential expression during hippocampal development. In cultured hippocampal neurons, the cellular distributions of Frizzleds vary greatly, some of them being localized at neurites, growth cones or synaptic sites. These findings suggest that the Wnt signaling pathway might be temporally and spatially fine tuned during the development of neuronal circuits through specific Frizzled receptors.
ESTHER : Varela-Nallar_2012_Cytoskeleton.(Hoboken)_69_528
PubMedSearch : Varela-Nallar_2012_Cytoskeleton.(Hoboken)_69_528
PubMedID: 22407911

Title : Synaptic defects associated with s-inclusion body myositis are prevented by copper - Aldunate_2012_Biometals_25_815
Author(s) : Aldunate R , Minniti AN , Rebolledo D , Inestrosa NC
Ref : Biometals , 25 :815 , 2012
Abstract : Sporadic-inclusion body myositis (s-IBM) is the most common skeletal muscle disorder to afflict the elderly, and is clinically characterized by skeletal muscle degeneration. Its progressive course leads to muscle weakness and wasting, resulting in severe disability. The exact pathogenesis of this disease is unknown and no effective treatment has yet been found. An intriguing aspect of s-IBM is that it shares several molecular abnormalities with Alzheimer's disease, including the accumulation of amyloid-beta-peptide (Abeta). Both disorders affect homeostasis of the cytotoxic fragment Abeta(1-42) during aging, but they are clinically distinct diseases. The use of animals that mimic some characteristics of a disease has become important in the search to elucidate the molecular mechanisms underlying the pathogenesis. With the aim of analyzing Abeta-induced pathology and evaluating the consequences of modulating Abeta aggregation, we used Caenorhabditis elegans that express the Abeta human peptide in muscle cells as a model of s-IBM. Previous studies indicate that copper treatment increases the number and size of amyloid deposits in muscle cells, and is able to ameliorate the motility impairments in Abeta transgenic C. elegans. Our recent studies show that neuromuscular synaptic transmission is defective in animals that express the Abeta-peptide and suggest a specific defect at the nicotine acetylcholine receptors level. Biochemical analyses show that copper treatment increases the number of amyloid deposits but decreases Abeta-oligomers. Copper treatment improves motility, synaptic structure and function. Our results suggest that Abeta-oligomers are the toxic Abeta species that trigger neuromuscular junction dysfunction.
ESTHER : Aldunate_2012_Biometals_25_815
PubMedSearch : Aldunate_2012_Biometals_25_815
PubMedID: 22573194

Title : The Cellular Prion Protein Prevents Copper-Induced Inhibition of P2X(4) Receptors - Lorca_2011_Int.J.Alzheimers.Dis_2011_706576
Author(s) : Lorca RA , Varela-Nallar L , Inestrosa NC , Huidobro-Toro JP
Ref : Int J Alzheimers Dis , 2011 :706576 , 2011
Abstract : Although the physiological function of the cellular prion protein (PrP(C)) remains unknown, several evidences support the notion of its role in copper homeostasis. PrP(C) binds Cu(2+) through a domain composed by four to five repeats of eight amino acids. Previously, we have shown that the perfusion of this domain prevents and reverses the inhibition by Cu(2+) of the adenosine triphosphate (ATP)-evoked currents in the P2X(4) receptor subtype, highlighting a modulatory role for PrP(C) in synaptic transmission through regulation of Cu(2+) levels. Here, we study the effect of full-length PrP(C) in Cu(2+) inhibition of P2X(4) receptor when both are coexpressed. PrP(C) expression does not significantly change the ATP concentration-response curve in oocytes expressing P2X(4) receptors. However, the presence of PrP(C) reduces the inhibition by Cu(2+) of the ATP-elicited currents in these oocytes, confirming our previous observations with the Cu(2+) binding domain. Thus, our observations suggest a role for PrP(C) in modulating synaptic activity through binding of extracellular Cu(2+).
ESTHER : Lorca_2011_Int.J.Alzheimers.Dis_2011_706576
PubMedSearch : Lorca_2011_Int.J.Alzheimers.Dis_2011_706576
PubMedID: 22114745

Title : Copper reduces Abeta oligomeric species and ameliorates neuromuscular synaptic defects in a C. elegans model of inclusion body myositis - Rebolledo_2011_J.Neurosci_31_10149
Author(s) : Rebolledo DL , Aldunate R , Kohn R , Neira I , Minniti AN , Inestrosa NC
Ref : Journal of Neuroscience , 31 :10149 , 2011
Abstract : Alzheimer's disease and inclusion body myositis (IBM) are disorders frequently found in the elderly and characterized by the presence of amyloid-beta peptide (Abeta) aggregates. We used Caenorhabditis elegans that express Abeta in muscle cells as a model of IBM, with the aim of analyzing Abeta-induced muscle pathology and evaluating the consequences of modulating Abeta aggregation. First, we tested whether the altered motility we observed in the Abeta transgenic strain could be the result of a compromised neuromuscular synapse. Our pharmacological analyses show that synaptic transmission is defective in our model and suggest a specific defect on nicotine-sensitive acetylcholine receptors (AChRs). Through GFP-coupled protein visualization, we found that synaptic dysfunction correlates with mislocalization of ACR-16, the AChR subunit essential for nicotine-triggered currents. Histological and biochemical analysis allowed us to determine that copper treatment increases the amyloid deposits and decreases Abeta oligomers in this model. Furthermore, copper treatment improves motility, ACR-16 localization, and synaptic function and delays Abeta-induced paralysis. Our results indicate that copper modulates Abeta-induced pathology and suggest that Abeta oligomers are triggering neuromuscular dysfunction. Our findings emphasize the importance of neuromuscular synaptic dysfunction and the relevance of modulating the amyloidogenic component as an alternative therapeutic approach for this debilitating disease.
ESTHER : Rebolledo_2011_J.Neurosci_31_10149
PubMedSearch : Rebolledo_2011_J.Neurosci_31_10149
PubMedID: 21752991

Title : The synaptic protein neuroligin-1 interacts with the amyloid beta-peptide. Is there a role in Alzheimer's disease? - Dinamarca_2011_Biochemistry_50_8127
Author(s) : Dinamarca MC , Weinstein D , Monasterio O , Inestrosa NC
Ref : Biochemistry , 50 :8127 , 2011
Abstract : Amyloid beta-peptide (Abeta) is the main component of the amyloid plaques associated with Alzheimer's disease (AD). In the early steps of the disease soluble Abeta oligomers are produced. According to the current "amyloid hypothesis" these oligomers can accumulate over time, leading progressively to the loss of synaptic function and the cognitive failure characteristic of AD. To understand the role of oligomeric Abeta species in AD pathology, it is important to understand the mechanism by which Abeta oligomers are targeted to synaptic junction. We report here the interaction between Abeta with neuroligin-1 (NL-1), a postsynaptic cell-adhesion protein specific for excitatory synapses, which shares a high degree of similarity with acetylcholinesterase, the first synaptic protein described to interact with Abeta. Using intrinsic fluorescence and surface plasmon resonance, we found that Abeta binds to the extracellular domain of NL-1 with a K(d) in the nanomolar range. In the case of NL-2, a postsynaptic cell-adhesion protein specific for inhibitory synapses, just a very weak interaction with Abeta was observed. Abeta polymerization analysis-studied by thioflavin-T assay and electron microscopy-indicated that NL-1 stabilized Abeta aggregates in vitro. Moreover, NL-1 acts as a nucleating factor during the Abeta aggregation process, stimulating the formation of Abeta oligomers. Besides, immunoprecipitation assays confirm that Abeta oligomers interact with NL-1 but not with NL-2. In conclusion, our results show that NL-1 interacts with Abeta increasing the formation of Abeta oligomers, suggesting that this interaction could triggers the targeting of Abeta oligomer to the postsynaptic regions of excitatory synapses.
ESTHER : Dinamarca_2011_Biochemistry_50_8127
PubMedSearch : Dinamarca_2011_Biochemistry_50_8127
PubMedID: 21838267

Title : Tetrahydrohyperforin prevents cognitive deficit, Abeta deposition, tau phosphorylation and synaptotoxicity in the APPswe\/PSEN1DeltaE9 model of Alzheimer's disease: a possible effect on APP processing - Inestrosa_2011_Transl.Psychiatry_1_e20
Author(s) : Inestrosa NC , Tapia-Rojas C , Griffith TN , Carvajal FJ , Benito MJ , Rivera-Dictter A , Alvarez AR , Serrano FG , Hancke JL , Burgos PV , Parodi J , Varela-Nallar L
Ref : Transl Psychiatry , 1 :e20 , 2011
Abstract : Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, amyloid-beta peptide (Abeta) accumulation and synaptic alterations. Previous studies indicated that hyperforin, a component of the St John's Wort, prevents Abeta neurotoxicity and some behavioral impairments in a rat model of AD. In this study we examined the ability of tetrahydrohyperforin (IDN5607), a stable hyperforin derivative, to prevent the cognitive deficit and synaptic impairment in an in vivo model of AD. In double transgenic APPswe/PSEN1DeltaE9 mice, IDN5706 improves memory and prevents the impairment of synaptic plasticity in a dose-dependent manner, inducing a recovery of long-term potentiation. In agreement with these findings, IDN5706 prevented the decrease in synaptic proteins in hippocampus and cortex. In addition, decreased levels of tau hyperphosphorylation, astrogliosis, and total fibrillar and oligomeric forms of Abeta were determined in double transgenic mice treated with IDN5706. In cultured cells, IDN5706 decreased the proteolytic processing of the amyloid precursor protein that leads to Abeta peptide generation. These findings indicate that IDN5706 ameliorates AD neuropathology and could be considered of therapeutic relevance in AD treatment.
ESTHER : Inestrosa_2011_Transl.Psychiatry_1_e20
PubMedSearch : Inestrosa_2011_Transl.Psychiatry_1_e20
PubMedID: 22832522

Title : Interactions of AChE with Abeta Aggregates in Alzheimer's Brain: Therapeutic Relevance of IDN 5706 - Carvajal_2011_Front.Mol.Neurosci_4_19
Author(s) : Carvajal FJ , Inestrosa NC
Ref : Front Mol Neurosci , 4 :19 , 2011
Abstract : Acetylcholinesterase (AChE; EC 3.1.1.7) plays a crucial role in the rapid hydrolysis of the neurotransmitter acetylcholine, in the central and peripheral nervous system and might also participate in non-cholinergic mechanism related to neurodegenerative diseases. Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, amyloid-beta (Abeta) peptide accumulation and synaptic alterations. We have previously shown that AChE is able to accelerate the Abeta peptide assembly into Alzheimer-type aggregates increasing its neurotoxicity. Furthermore, AChE activity is altered in brain and blood of Alzheimer's patients. The enzyme associated to amyloid plaques changes its enzymatic and pharmacological properties, as well as, increases its resistant to low pH, inhibitors and excess of substrate. Here, we reviewed the effects of IDN 5706, a hyperforin derivative that has potential preventive effects on the development of AD. Our results show that treatment with IDN 5706 for 10 weeks increases brain AChE activity in 7-month-old double transgenic mice (APP(SWE)-PS1) and decreases the content of AChE associated with different types of amyloid plaques in this Alzheimer's model. We concluded that early treatment with IDN 5706 decreases AChE-Abeta interaction and this effect might be of therapeutic interest in the treatment of AD.
ESTHER : Carvajal_2011_Front.Mol.Neurosci_4_19
PubMedSearch : Carvajal_2011_Front.Mol.Neurosci_4_19
PubMedID: 21949501

Title : Neurobiological effects of Hyperforin and its potential in Alzheimer's disease therapy - Griffith_2010_Curr.Med.Chem_17_391
Author(s) : Griffith TN , Varela-Nallar L , Dinamarca MC , Inestrosa NC
Ref : Curr Med Chem , 17 :391 , 2010
Abstract : St. John's Wort (SJW) has been used medicinally for over 5,000 years. Relatively recently, one of its phloroglucinol derivatives, hyperforin, has emerged as a compound of interest. Hyperforin first gained attention as the constituent of SJW responsible for its antidepressant effects. Since then, several of its neurobiological effects have been described, including neurotransmitter re-uptake inhibition, the ability to increase intracellular sodium and calcium levels, canonical transient receptor potential 6 (TRPC6) activation, N-methyl-D-aspartic acid (NMDA) receptor antagonism as well as antioxidant and anti-inflammatory properties. Until recently, its pharmacological actions outside of depression had not been investigated. However, hyperforin has been shown to have cognitive enhancing and memory facilitating properties. Importantly, it has been shown to have neuroprotective effects against Alzheimer's disease (AD) neuropathology, including the ability to disassemble amyloid-beta (Abeta) aggregates in vitro, decrease astrogliosis and microglia activation, as well as improve spatial memory in vivo. This review will examine some of the early studies involving hyperforin and its effects in the central nervous system (CNS), with an emphasis on its potential use in AD therapy. With further investigation, hyperforin could emerge to be a likely therapeutical candidate in the treatment of this disease.
ESTHER : Griffith_2010_Curr.Med.Chem_17_391
PubMedSearch : Griffith_2010_Curr.Med.Chem_17_391
PubMedID: 20015041

Title : Wnt signaling modulates pre- and postsynaptic maturation: therapeutic considerations - Farias_2010_Dev.Dyn_239_94
Author(s) : Farias GG , Godoy JA , Cerpa W , Varela-Nallar L , Inestrosa NC
Ref : Developmental Dynamics , 239 :94 , 2010
Abstract : Wnt signaling regulates a wealth of aspects of nervous system development and function in embryonic stages and in adulthood. The expression of Wnt ligands and components of the Wnt signaling machinery in early stages of neural development has been related to its role in neurite patterning and in synaptogenesis. Moreover, its expression in the mature nervous system suggests a role for this pathway in synaptic maintenance and function. Therefore, it is of crucial relevance the understanding of the mechanisms by which Wnt signaling regulates these processes. Herein, we discuss how different Wnt ligands, acting through different Wnt signaling pathways, operate in pre- and postsynaptic regions to modulate synapse structure and function. We also elaborate on the idea that Wnt signaling pathways are a target for the treatment of neurodegenerative diseases that affect synaptic integrity, such as Alzheimer's disease.
ESTHER : Farias_2010_Dev.Dyn_239_94
PubMedSearch : Farias_2010_Dev.Dyn_239_94
PubMedID: 19681159

Title : Synaptic clustering of PSD-95 is regulated by c-Abl through tyrosine phosphorylation - Perez_2010_J.Neurosci_30_3728
Author(s) : Perez de Arce K , Varela-Nallar L , Farias O , Cifuentes A , Bull P , Couch BA , Koleske AJ , Inestrosa NC , Alvarez AR
Ref : Journal of Neuroscience , 30 :3728 , 2010
Abstract : The c-Abl tyrosine kinase is present in mouse brain synapses, but its precise synaptic function is unknown. We found that c-Abl levels in the rat hippocampus increase postnatally, with expression peaking at the first postnatal week. In 14 d in vitro hippocampal neuron cultures, c-Abl localizes primarily to the postsynaptic compartment, in which it colocalizes with the postsynaptic scaffold protein postsynaptic density protein-95 (PSD-95) in apposition to presynaptic markers. c-Abl associates with PSD-95, and chemical or genetic inhibition of c-Abl kinase activity reduces PSD-95 tyrosine phosphorylation, leading to reduced PSD-95 clustering and reduced synapses in treated neurons. c-Abl can phosphorylate PSD-95 on tyrosine 533, and mutation of this residue reduces the ability of PSD-95 to cluster at postsynaptic sites. Our results indicate that c-Abl regulates synapse formation by mediating tyrosine phosphorylation and clustering of PSD-95.
ESTHER : Perez_2010_J.Neurosci_30_3728
PubMedSearch : Perez_2010_J.Neurosci_30_3728
PubMedID: 20220006

Title : Wingless-type family member 5A (Wnt-5a) stimulates synaptic differentiation and function of glutamatergic synapses - Varela-Nallar_2010_Proc.Natl.Acad.Sci.U.S.A_107_21164
Author(s) : Varela-Nallar L , Alfaro IE , Serrano FG , Parodi J , Inestrosa NC
Ref : Proc Natl Acad Sci U S A , 107 :21164 , 2010
Abstract : Growing evidence indicates that Wingless-type (Wnt) signaling plays an important role in the maturation of the central nervous system. We report here that Wingless-type family member 5A (Wnt-5a) is expressed early in development and stimulates dendrite spine morphogenesis, inducing de novo formation of spines and increasing the size of the preexisting ones in hippocampal neurons. Wnt-5a increased intracellular calcium concentration in dendritic processes and the amplitude of NMDA spontaneous miniature currents. Acute application of Wnt-5a increased the amplitude of field excitatory postsynaptic potentials (fEPSP) in hippocampal slices, an effect that was prevented by calcium-channel blockers. The physiological relevance of our findings is supported by studies showing that Wnt scavengers decreased spine density, miniature excitatory postsynaptic currents, and fEPSP amplitude. We conclude that Wnt-5a stimulates different aspects of synaptic differentiation and plasticity in the mammalian central nervous system.
ESTHER : Varela-Nallar_2010_Proc.Natl.Acad.Sci.U.S.A_107_21164
PubMedSearch : Varela-Nallar_2010_Proc.Natl.Acad.Sci.U.S.A_107_21164
PubMedID: 21084636

Title : Adult hippocampal neurogenesis in aging and Alzheimer's disease - Varela-Nallar_2010_Birth.Defects.Res.C.Embryo.Today_90_284
Author(s) : Varela-Nallar L , Aranguiz FC , Abbott AC , Slater PG , Inestrosa NC
Ref : Birth Defects Res C Embryo Today , 90 :284 , 2010
Abstract : Adult neurogenesis occurs in the subgranular zone of the hippocampal dentate gyrus and the subventricular zone of the lateral ventricles. This process is highly regulated by intrinsic and extrinsic factors, which may control the proliferation and/or maturation of neural progenitor cells. Adult-born neurons are integrated in preexisting networks and may have functional implications for adult brain. Here we attempt to summarize relevant findings concerning the physiological role of adult neurogenesis mainly focused on the subgranular zone, and to discuss the reduced neurogenesis observed during aging and the factors that have been involved in this phenomenon. Finally, we focus on hippocampal neurogenesis in Alzheimer's disease, reviewing animal models of the disease used for the study of this process and the conclusions that have been drawn in this context.
ESTHER : Varela-Nallar_2010_Birth.Defects.Res.C.Embryo.Today_90_284
PubMedSearch : Varela-Nallar_2010_Birth.Defects.Res.C.Embryo.Today_90_284
PubMedID: 21181889

Title : Calcium\/calmodulin-dependent protein kinase type IV is a target gene of the Wnt\/beta-catenin signaling pathway - Arrazola_2009_J.Cell.Physiol_221_658
Author(s) : Arrazola MS , Varela-Nallar L , Colombres M , Toledo EM , Cruzat F , Pavez L , Assar R , Aravena A , Gonzalez M , Montecino M , Maass A , Martinez S , Inestrosa NC
Ref : Journal of Cellular Physiology , 221 :658 , 2009
Abstract : Calcium/calmodulin-dependent protein kinase IV (CaMKIV) plays a key role in the regulation of calcium-dependent gene expression. The expression of CaMKIV and the activation of CREB regulated genes are involved in memory and neuronal survival. We report here that: (a) a bioinformatic analysis of 15,476 promoters of the human genome predicted several Wnt target genes, being CaMKIV a very interesting candidate; (b) CaMKIV promoter contains TCF/LEF transcription motifs similar to those present in Wnt target genes; (c) biochemical studies indicate that lithium and the canonical ligand Wnt-3a induce CaMKIV mRNA and protein expression levels in rat hippocampal neurons as well as CaMKIV promoter activity; (d) treatment of hippocampal neurons with Wnt-3a increases the binding of beta-catenin to the CaMKIV promoter: (e) In vivo activation of the Wnt signaling improve spatial memory impairment and restores the expression of CaMKIV in a mice double transgenic model for Alzheimer's disease which shows decreased levels of the kinase. We conclude that CaMKIV is regulated by the Wnt signaling pathway and that its expression could play a role in the neuroprotective function of the Wnt signaling against the Alzheimer's amyloid peptide.
ESTHER : Arrazola_2009_J.Cell.Physiol_221_658
PubMedSearch : Arrazola_2009_J.Cell.Physiol_221_658
PubMedID: 19711354

Title : Overexpression of amyloid precursor protein increases copper content in HEK293 cells - Suazo_2009_Biochem.Biophys.Res.Commun_382_740
Author(s) : Suazo M , Hodar C , Morgan C , Cerpa W , Cambiazo V , Inestrosa NC , Gonzalez M
Ref : Biochemical & Biophysical Research Communications , 382 :740 , 2009
Abstract : Amyloid precursor protein (APP) is a transmembrane glycoprotein widely expressed in mammalian tissues and plays a central role in Alzheimer's disease. However, its physiological function remains elusive. Cu(2+) binding and reduction activities have been described in the extracellular APP135-156 region, which might be relevant for cellular copper uptake and homeostasis. Here, we assessed Cu(2+) reduction and (64)Cu uptake in two human HEK293 cell lines overexpressing APP. Our results indicate that Cu(2+) reduction increased and cells accumulated larger levels of copper, maintaining cell viability at supra-physiological levels of Cu(2+) ions. Moreover, wild-type cells exposed to both Cu(2+) ions and APP135-155 synthetic peptides increased copper reduction and uptake. Complementation of function studies in human APP751 transformed Fre1 defective Saccharomyces cerevisiae cells rescued low Cu(2+) reductase activity and increased (64)Cu uptake. We conclude that Cu(2+) reduction activity of APP facilitates copper uptake and may represent an early step in cellular copper homeostasis.
ESTHER : Suazo_2009_Biochem.Biophys.Res.Commun_382_740
PubMedSearch : Suazo_2009_Biochem.Biophys.Res.Commun_382_740
PubMedID: 19318086

Title : The role of Wnt signaling in neuroprotection - Cerpa_2009_Drug.News.Perspect_22_579
Author(s) : Cerpa W , Toledo EM , Varela-Nallar L , Inestrosa NC
Ref : Drug News Perspect , 22 :579 , 2009
Abstract : The Wnt signaling pathway has a role in several cellular processes, including cellular communication, embryonic development and cancer. Recent studies show that the Wnt pathway also has an important role in some aspects of neuronal circuit development, such as neuronal migration, synaptic differentiation, mature synapse modulation and synaptic plasticity. Wnt signaling begins during neural development and is crucial for long-term potentiation in the adult brain. The Wnt pathway may have potential in the prevention of neurodegenerative diseases that involve synaptic impairment. Several years ago our laboratory found a relationship between the loss of Wnt signaling and amyloid-beta-peptide (Abeta) neurotoxicity, which is involved in Alzheimer's disease (AD). The activation of the Wnt signaling cascade prevents Abeta-dependent cytotoxic effects. We proposed that beta-catenin-dependent Wnt ligands have a role in the modulation of presynaptic processes such as neurotransmitter release. beta-catenin-independent Wnt signaling controls the postsynaptic site, increasing the incorporation of PSD-95 and glutamatergic receptors in the postsynaptic region. This could prevent the effects of Abeta exposure at the postsynaptic level. The study of the Wnt pathway is a promising approach in the search for possible targets to fight the deleterious effects of neurodegenerative conditions such as AD.
ESTHER : Cerpa_2009_Drug.News.Perspect_22_579
PubMedSearch : Cerpa_2009_Drug.News.Perspect_22_579
PubMedID: 20140278

Title : Role of the Wnt receptor Frizzled-1 in presynaptic differentiation and function - Varela-Nallar_2009_Neural.Dev_4_41
Author(s) : Varela-Nallar L , Grabowski CP , Alfaro IE , Alvarez AR , Inestrosa NC
Ref : Neural Dev , 4 :41 , 2009
Abstract : BACKGROUND: The Wnt signaling pathway regulates several fundamental developmental processes and recently has been shown to be involved in different aspects of synaptic differentiation and plasticity. Some Wnt signaling components are localized at central synapses, and it is thus possible that this pathway could be activated at the synapse.
RESULTS: We examined the distribution of the Wnt receptor Frizzled-1 in cultured hippocampal neurons and determined that this receptor is located at synaptic contacts co-localizing with presynaptic proteins. Frizzled-1 was found in functional synapses detected with FM1-43 staining and in synaptic terminals from adult rat brain. Interestingly, overexpression of Frizzled-1 increased the number of clusters of Bassoon, a component of the active zone, while treatment with the extracellular cysteine-rich domain (CRD) of Frizzled-1 decreased Bassoon clustering, suggesting a role for this receptor in presynaptic differentiation. Consistent with this, treatment with the Frizzled-1 ligand Wnt-3a induced presynaptic protein clustering and increased functional presynaptic recycling sites, and these effects were prevented by co-treatment with the CRD of Frizzled-1. Moreover, in synaptically mature neurons Wnt-3a was able to modulate the kinetics of neurotransmitter release. CONCLUSION: Our results indicate that the activation of the Wnt pathway through Frizzled-1 occurs at the presynaptic level, and suggest that the synaptic effects of the Wnt signaling pathway could be modulated by local activation through synaptic Frizzled receptors.
ESTHER : Varela-Nallar_2009_Neural.Dev_4_41
PubMedSearch : Varela-Nallar_2009_Neural.Dev_4_41
PubMedID: 19883499

Title : Methionine sulfoxide reductase A expression is regulated by the DAF-16\/FOXO pathway in Caenorhabditis elegans - Minniti_2009_Aging.Cell_8_690
Author(s) : Minniti AN , Cataldo R , Trigo C , Vasquez L , Mujica P , Leighton F , Inestrosa NC , Aldunate R
Ref : Aging Cell , 8 :690 , 2009
Abstract : The methionine sulfoxide reductase system has been implicated in aging and protection against oxidative stress. This conserved system reverses the oxidation of methionine residues within proteins. We analyzed one of the components of this system, the methionine sulfoxide reductase A gene, in Caenorhabditis elegans. We found that the msra-1 gene is expressed in most tissues, particularly in the intestine and the nervous system. Worms carrying a deletion of the msra-1 gene are more sensitive to oxidative stress, show chemotaxis and locomotory defects, and a 30% decrease in median survival. We established that msra-1 expression decreases during aging and is regulated by the DAF-16/FOXO3a transcription factor. The absence of this enzyme decreases median survival and affects oxidative stress resistance of long lived daf-2 worms. A similar effect of MSRA-1 absence in wild-type and daf-2 (where most antioxidant enzymes are activated) backgrounds, suggests that the lack of this member of the methionine repair system cannot be compensated by the general antioxidant response. Moreover, FOXO3a directly activates the human MsrA promoter in a cell culture system, implying that this could be a conserved mechanism of MsrA regulation. Our results suggest that repair of oxidative damage in proteins influences the rate at which tissues age. This repair mechanism, rather than the general decreased of radical oxygen species levels, could be one of the main determinants of organisms' lifespan.
ESTHER : Minniti_2009_Aging.Cell_8_690
PubMedSearch : Minniti_2009_Aging.Cell_8_690
PubMedID: 19747232

Title : Intracellular amyloid formation in muscle cells of Abeta-transgenic Caenorhabditis elegans: determinants and physiological role in copper detoxification - Minniti_2009_Mol.Neurodegener_4_2
Author(s) : Minniti AN , Rebolledo DL , Grez PM , Fadic R , Aldunate R , Volitakis I , Cherny RA , Opazo C , Masters C , Bush AI , Inestrosa NC
Ref : Mol Neurodegener , 4 :2 , 2009
Abstract : BACKGROUND: The amyloid beta-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Abeta aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Abeta is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Abeta is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly.
RESULTS: In the present work, we found that intracellular Abeta aggregation in muscle cells of Caenorhabditis elegans overexpressing Abeta peptide is affected by two single amino acid substitutions, E22G (Arctic) and V18A (NIC). Both variations show decrease intracellular amyloidogenesis compared to wild type Abeta. We show that intracellular amyloid aggregation of wild type Abeta is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Abeta-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates. CONCLUSION: Our data show that intracellular Abeta amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Abeta aggregation may be part of a cell protective mechanism.
ESTHER : Minniti_2009_Mol.Neurodegener_4_2
PubMedSearch : Minniti_2009_Mol.Neurodegener_4_2
PubMedID: 19126228

Title : Amyloid-cholinesterase interactions. Implications for Alzheimer's disease - Inestrosa_2008_FEBS.J_275_625
Author(s) : Inestrosa NC , Dinamarca MC , Alvarez A
Ref : Febs J , 275 :625 , 2008
Abstract : Acetylcholinesterase is an enzyme associated with senile plaques. Biochemical studies have indicated that acetylcholinesterase induces amyloid fibril formation by interaction throughout the peripherical anionic site of the enzyme forming highly toxic acetylcholinesterase-amyloid-beta peptide (Abeta) complexes. The pro-aggregating acetylcholinesterase effect is associated with the intrinsic amyloidogenic properties of the corresponding Abeta peptide. The neurotoxicity induced by acetylcholinesterase-Abeta complexes is higher than the that induced by the Abeta peptide alone, both in vitro and in vivo. The fact that acetylcholinesterase accelerates amyloid formation and the effect is sensitive to peripherical anionic site blockers of the enzyme, suggests that specific and new acetylcholinesterase inhibitors may well provide an attractive possibility for treating Alzheimer's disease. Recent studies also indicate that acetylcholinesterase induces the aggregation of prion protein with a similar dependence on the peripherical anionic site.
ESTHER : Inestrosa_2008_FEBS.J_275_625
PubMedSearch : Inestrosa_2008_FEBS.J_275_625
PubMedID: 18205831

Title : Release of acetylcholinesterase (AChE) from beta-amyloid plaques assemblies improves the spatial memory impairments in APP-transgenic mice - Dinamarca_2008_Chem.Biol.Interact_175_142
Author(s) : Dinamarca MC , Arrazola M , Toledo E , Cerpa WF , Hancke J , Inestrosa NC
Ref : Chemico-Biological Interactions , 175 :142 , 2008
Abstract : The major protein constituent of amyloid deposits in Alzheimer's disease (AD) is the amyloid-beta-peptide (Abeta). Amyloid deposits contain "chaperone molecules" which play critical roles in amyloid formation and toxicity. In the present work, we test an analog of hyperforin (IDN 5706) which releases the AChE from both the Abeta fibrils and the AChE-Abeta burdens in transgenic mice. Hyperforin is an acylphloroglucinol compound isolated from Hypericum perforatum (St. John's Wort), which is able to prevent the Abeta-induced spatial memory impairments and Abeta neurotoxicity. Altogether this gathered evidence indicates the important role of AChE in the neurotoxicity of Abeta plaques and finding new compounds which decrease the AChE-Abeta interaction may be a putative therapeutic agent to fight the disease.
ESTHER : Dinamarca_2008_Chem.Biol.Interact_175_142
PubMedSearch : Dinamarca_2008_Chem.Biol.Interact_175_142
PubMedID: 18599028

Title : Frizzled-1 is involved in the neuroprotective effect of Wnt3a against Abeta oligomers - Chacon_2008_J.Cell.Physiol_217_215
Author(s) : Chacon MA , Varela-Nallar L , Inestrosa NC
Ref : Journal of Cellular Physiology , 217 :215 , 2008
Abstract : The activation of the canonical Wnt signaling pathway protects hippocampal neurons against the toxicity of Alzheimer's amyloid-beta-peptide (Abeta), however, the role played by the Wnt receptors Frizzleds, has not been studied. We report here that Frizzled-1 mediates the activation of the canonical Wnt/beta-catenin pathway by Wnt3a in PC12 cells. In addition, the protective effect of Wnt3a against the toxicity of Abeta oligomers was modulated by Frizzled-1 expression levels in both PC12 cells and hippocampal neurons. Over-expression of Frizzled-1 significantly increased cell survival induced by Wnt3a and diminished caspase-3 activation, while knocking-down Frizzled-1 expression by antisense oligonucleotides decreased the Wnt3a protection. Over-expression of wild-type beta-catenin, but not a transcriptionally inactive mutated version, prevented the toxicity of Abeta suggesting that the transcription of Wnt target genes may be involved in these events. This was confirmed by co-transfecting both Frizzled-1 and the inactive form of beta-catenin, which does not elicited protection levels similar to those showed with endogenous beta-catenin. Our results indicate that Wnt3a protects from Abeta-oligomers toxicity by activating the canonical Wnt signaling pathway through the Frizzled-1 receptor, suggesting a therapeutic potential for this signaling pathway in the treatment of Alzheimer's disease.
ESTHER : Chacon_2008_J.Cell.Physiol_217_215
PubMedSearch : Chacon_2008_J.Cell.Physiol_217_215
PubMedID: 18521822

Title : Inclusion body myositis: a view from the Caenorhabditis elegans muscle - Rebolledo_2008_Mol.Neurobiol_38_178
Author(s) : Rebolledo DL , Minniti AN , Grez PM , Fadic R , Kohn R , Inestrosa NC
Ref : Molecular Neurobiology , 38 :178 , 2008
Abstract : Inclusion body myositis (IBM) is the most common myopathy in people over 50 years of age. It involves an inflammatory process that, paradoxically, does not respond to anti-inflammatory drugs. A key feature of IBM is the presence of amyloid-beta-peptide aggregates called amyloid deposits, which are also characteristic of Alzheimer's disease. The use of animals that mimic at least some characteristics of a disease has become very important in the quest to elucidate the molecular mechanisms underlying this and other pathogeneses. Although there are some transgenic mouse strains that recreate some aspects of IBM, in this review, we hypothesize that the great degree of similarity between nematode and human genes known to be involved in IBM as well as the considerable conservation of biological mechanisms across species is an important feature that must be taken into consideration when deciding on the use of this nematode as a model. Straightforward laboratory techniques (culture, transformation, gene knockdown, genetic screenings, etc.) as well as anatomical, physiological, and behavioral characteristics add to the value of this model. In the present work, we review evidence that supports the use of Caenorhabditis elegans as a biological model for IBM.
ESTHER : Rebolledo_2008_Mol.Neurobiol_38_178
PubMedSearch : Rebolledo_2008_Mol.Neurobiol_38_178
PubMedID: 18773311

Title : Structure-function implications in Alzheimer's disease: effect of Abeta oligomers at central synapses - Cerpa_2008_Curr.Alzheimer.Res_5_233
Author(s) : Cerpa W , Dinamarca MC , Inestrosa NC
Ref : Curr Alzheimer Res , 5 :233 , 2008
Abstract : Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the growing population of elderly people. A characteristic of AD is the accumulation of plaques in the brain of AD patients, and theses plaques mainly consist of aggregates of amyloid beta-peptide (Abeta). All converging lines of evidence suggest that progressive accumulation of the Abeta plays a central role in the genesis of Alzheimer's disease and it was long understood that Abeta had to be assembled into extracellular amyloid fibrils to exert its cytotoxic effects. This process could be modulated by molecular chaperones which inhibit or accelerate the amyloid formation. The enzyme Acetylcholinesterase (AChE) induces Abeta fibrils formation, forming a stable complex highly neurotoxic. On the other hand, laminin inhibit the Abeta fibrils formation and depolymerizate Abeta fibrils also. Over the past decade, data have emerged from the use of several sources of Abeta (synthetic, cell culture, transgenic mice and human brain) to suggest that intermediate species called Abeta oligomers are also injurious. Accumulating evidence suggests that soluble forms of Abeta are indeed the proximate effectors of synapse loss and neuronal injury. On the other hand, the member of the Wnt signaling pathway, beta-catenin was markedly reduced in AD patients carrying autosomal dominant PS-1. Also, neurons incubated with Abeta revealed a significant dose-dependent decrease in the levels of cytosolic beta-catenin an effect which was reversed in cells co-incubated with increasing concentrations of lithium, an activator of Wnt signaling pathway. Wnt signaling blocks the behavioural impairments induced by hippocampal injection of Abeta, therefore the activation of Wnt signaling protects against the Abeta neurotoxicity. Here we review recent progress about Abeta structure and function, from the formation of amyloid fibrils and some molecular chaperones which modulate the amyloidogenesic process to synaptic damage induce by Abeta oligomers.
ESTHER : Cerpa_2008_Curr.Alzheimer.Res_5_233
PubMedSearch : Cerpa_2008_Curr.Alzheimer.Res_5_233
PubMedID: 18537540

Title : Synaptotoxicity in Alzheimer's disease: the Wnt signaling pathway as a molecular target - Inestrosa_2007_IUBMB.Life_59_316
Author(s) : Inestrosa NC , Varela-Nallar L , Grabowski CP , Colombres M
Ref : IUBMB Life , 59 :316 , 2007
Abstract : Recent evidence supports a role of the Wnt pathway in neurodegenerative disorders such as Alzheimer's disease (AD). A relationship between amyloid-beta-peptide (Abeta)-induced neurotoxicity and a decrease in the cytoplasmatic levels of beta-catenin has been proposed. Also, the inhibition of glycogen synthase kinase (GSK-3beta), a central modulator of the pathway, protects rat hippocampal neurons from Abeta-induced damage. Interestingly, during the progression of AD, it has been described that active GSK-3beta is found in neuronal cell bodies and neurites, co-localizing with pre-neurofibrillary tangles observed in disease brains. Since Abeta oligomers are associated with the post-synaptic region and we have found that the non-canonical Wnt signaling modulates PSD-95 and glutamate receptors, we propose that the synaptic target for Abeta oligomers in AD is the postsynaptic region and at the molecular level is the non-canonical Wnt signaling pathway. Altogether, our evidence suggests that a sustained loss of Wnt signaling function may be involved in the Abeta-dependent neurodegeneration observed in AD brains and that the activation of this signaling pathway could be of therapeutic interest in AD.
ESTHER : Inestrosa_2007_IUBMB.Life_59_316
PubMedSearch : Inestrosa_2007_IUBMB.Life_59_316
PubMedID: 17505971

Title : Localization, specific activity, and molecular forms of acetylcholinesterase in developmental stages of the cestode Mesocestoides corti - Kemmerling_2006_J.Cell.Physiol_206_503
Author(s) : Kemmerling U , Cabrera G , Campos EO , Inestrosa NC , Galanti N
Ref : Journal of Cellular Physiology , 206 :503 , 2006
Abstract : The nervous system of flatworms is quite simple although there is increasing evidence indicating that it is chemically complex. Studies of the nervous system in these animals have only been performed in the larval stage or in the adult worms, which are easy to obtain in nature, while the description of the nervous system in developing stages of these organisms is missing. Mesocestoides corti is a parasitic platyhelminth whose larvae can be induced in vitro to develop to adult, sexually mature worms, opening the possibility of studying the nervous system of a flatworm in different stages of development. Here, we describe the presence, activity, location, and molecular forms of acetylcholinesterase (AChE) in different stages of development of M. corti, from the larvae to adult forms of this endoparasite, obtained in in vitro cultures after induction of the larval stage with trypsin. Our results point to AChE as a molecular marker of the nervous system in platyhelminthes. The change in molecular forms of this enzyme and the increase in its activity during development from larvae to adult worm may reflect the presence of a more complex nervous system, necessary to adjust and coordinate the movement of a much bigger structure. A relationship between the development of the reproductive apparatus in segmented and adult worms with a more complex nervous system in these stages is also apparent. Finally, our study opens the possibility of applying anti-AChE as more effective therapeutic strategies against cestode parasites.
ESTHER : Kemmerling_2006_J.Cell.Physiol_206_503
PubMedSearch : Kemmerling_2006_J.Cell.Physiol_206_503
PubMedID: 16155922

Title : Role of copper in prion diseases: deleterious or beneficial? - Varela-Nallar_2006_Curr.Pharm.Des_12_2587
Author(s) : Varela-Nallar L , Gonzalez A , Inestrosa NC
Ref : Curr Pharm Des , 12 :2587 , 2006
Abstract : Prion diseases are fatal neurodegenerative disorders associated with conformational conversion of the cellular prion protein (PrP(C)) into an isoform designated PrP(Sc). The pathogenic mechanism that links this conformational distortion with the development of prion diseases is unknown. PrP(C) is a GPI-anchored cell surface protein that associates with lipid rafts, undergoes endocytosis and recycles. Although the physiological function of PrP(C) remains unknown it has been related with a number of processes, including cellular copper transport and metabolism. PrP(C) has two copper binding domains and copper induces changes in PrP(C) conformation and endocytic behavior. However, the role of copper in prion diseases is unclear. PrP(C) expression and interaction with PrP(Sc) are required for prion progression. Therefore, factors that modify PrP(C) expression levels, conformation, intracellular trafficking and segregation into membranous microdomains could change the opportunities for and the quality of PrP(C) interactions with PrP(Sc) and thus influence prion pathogenesis. Here we discuss the potential of copper as modifier of these processes, attempting to integrate apparently contradictory observations which so far left uncertain whether copper exerts beneficial or detrimental effects upon prion diseases. The outcome of copper effects might be the resultant of two opposite conditions: one promoting misfolding of PrP(C) leading to prion conversion and the other promoting PrP(C) trafficking through pathways that prevent PrP(Sc)-PrP(C) interaction. Which of these predominates might vary under distinct conditions that need to be defined before deciding on the feasibility of either incorporating or avoiding metal influences in prion disease therapies.
ESTHER : Varela-Nallar_2006_Curr.Pharm.Des_12_2587
PubMedSearch : Varela-Nallar_2006_Curr.Pharm.Des_12_2587
PubMedID: 16842180

Title : The functional links between prion protein and copper - Varela-Nallar_2006_Biol.Res_39_39
Author(s) : Varela-Nallar L , Toledo EM , Chacon MA , Inestrosa NC
Ref : Biol Res , 39 :39 , 2006
Abstract : Prion diseases are fatal neurodegenerative disorders associated with the conversion of the cellular prion protein (PrPC) into a pathologic isoform. Although the physiological function of PrPC remains unknown, evidence relates PrPC to copper metabolism and oxidative stress as suggested by its copper-binding properties in the N-terminal octapeptide repeat region. This region also reduces copper ions in vitro, and this reduction ability is associated with the neuroprotection exerted by the octarepeat region against copper in vivo. In addition, the promoter region of the PrPC gene contains putative metal response elements suggesting it may be regulated by heavy metals. Here we address some of the evidence that support a physiological link between PrPC and copper. Also, in vivo experiments suggesting the physiological relevance of PrPC interaction with heparan sulfate proteoglycans are discussed.
ESTHER : Varela-Nallar_2006_Biol.Res_39_39
PubMedSearch : Varela-Nallar_2006_Biol.Res_39_39
PubMedID: 16629163

Title : Induction of cellular prion protein gene expression by copper in neurons - Varela-Nallar_2006_Am.J.Physiol.Cell.Physiol_290_C271
Author(s) : Varela-Nallar L , Toledo EM , Larrondo LF , Cabral AL , Martins VR , Inestrosa NC
Ref : American Journal of Physiology Cell Physiol , 290 :C271 , 2006
Abstract : Prion diseases are caused by the conformational transition of the native alpha-helical cellular prion protein (PrPC) into a beta-sheet pathogenic isoform. However, the normal physiological function of PrPC remains elusive. We report herein that copper induces PrPC expression in primary hippocampal and cortical neurons. PrPC induced by copper has a normal glycosylation pattern, is proteinase K-sensitive and reaches the cell surface attached by a glycosyl phosphatidylinositol anchor. Immunofluorescence analysis revealed that copper induces PrPC levels in the cell surface and in an intracellular compartment that we identified as the Golgi complex. In addition, copper induced the activity of a reporter vector driven by the rat PrPC gene (Prnp) promoter stably transfected into PC12 cells, whereas no effect was observed in glial C6 clones. Also cadmium, but not zinc or manganese, upregulated Prnp promoter activity in PC12 clones. Progressive deletions of the promoter revealed that the region essential for copper modulation contains a putative metal responsive element. Although electrophoretic mobility shift assay demonstrated nuclear protein binding to this element, supershift analysis showed that this is not a binding site for the metal responsive transcription factor-1 (MTF-1). The MTF-1-independent transcriptional activation of Prnp is supported by the lack of Prnp promoter activation by zinc. These findings demonstrate that Prnp expression is upregulated by copper in neuronal cells by an MTF-1-independent mechanism, and suggest a metal-specific modulation of Prnp in neurons.
ESTHER : Varela-Nallar_2006_Am.J.Physiol.Cell.Physiol_290_C271
PubMedSearch : Varela-Nallar_2006_Am.J.Physiol.Cell.Physiol_290_C271
PubMedID: 16148034

Title : Human-like rodent amyloid-beta-peptide determines Alzheimer pathology in aged wild-type Octodon degu - Inestrosa_2005_Neurobiol.Aging_26_1023
Author(s) : Inestrosa NC , Reyes AE , Chacon MA , Cerpa W , Villalon A , Montiel J , Merabachvili G , Aldunate R , Bozinovic F , Aboitiz F
Ref : Neurobiology of Aging , 26 :1023 , 2005
Abstract : It is generally accepted that human Alzheimer's disease (AD) neuropathology markers are completely absent in rodent brains. We report here that an aged wild-type South American rodent, Octodon degu, expresses neuronal beta-amyloid precursor protein (beta-APP695) displaying both intracellular and extracellular deposits of amyloid-beta-peptide (Abeta), intracellular accumulations of tau-protein and ubiquitin, a strong astrocytic response and acetylcholinesterase (AChE)-rich pyramidal neurons. The high amino acid homology (97.5%) between deguAbeta and humanAbeta sequences is probably a major factor in the appearance of AD markers in this aged rodent. Our results indicate that aged O. degu constitutes the first wild-type rodent model for neurodegenerative processes associated to AD.
ESTHER : Inestrosa_2005_Neurobiol.Aging_26_1023
PubMedSearch : Inestrosa_2005_Neurobiol.Aging_26_1023
PubMedID: 15748782

Title : Acetylcholinesterase interaction with Alzheimer amyloid beta - Inestrosa_2005_Subcell.Biochem_38_299
Author(s) : Inestrosa NC , Sagal JP , Colombres M
Ref : Subcell Biochem , 38 :299 , 2005
Abstract : Acetylcholinesterase (AChE) is an enzyme involved in cholinergic and non-cholinergic functions in both the central and peripheral nervous system, most of the AChE is found as a tetrameric form bound to neuronal membranes. Early cytochemical studies have demonstrated that the AChE associated with senile plaques differs enzymatically from the AChE associated with neurons in several respects. Biochemical studies indicated that AChE induces amyloid fibril formation and form highly toxic AChE-Abeta complexes. A 3.5 kDa peptide containing a tryptophan of the enzyme peripheral binding site (PAS) mimics the effect of the whole enzyme on amyloid formation. The neurotoxicity induced by AChE-Abeta complexes indicated that they trigger more neurodegeneration than those of the Abeta peptide alone, both in vitro (hippocampal neurons) and in vivo (rats injected in the dorsal hippocampus as a model of Alzheimer). The fact that AChE is able to accelerate amyloid formation and that such effect is sensitive to drugs that block PAS of the enzyme, suggests that specific and new AChE inhibitors may well provide an attractive possibility for treating Alzheimer's disease.
ESTHER : Inestrosa_2005_Subcell.Biochem_38_299
PubMedSearch : Inestrosa_2005_Subcell.Biochem_38_299
PubMedID: 15709485

Title : The anti-inflammatory and cholinesterase inhibitor bifunctional compound IBU-PO protects from beta-amyloid neurotoxicity by acting on Wnt signaling components - Farias_2005_Neurobiol.Dis_18_176
Author(s) : Farias GG , Godoy JA , Vazquez MC , Adani R , Meshulam H , Avila J , Amitai G , Inestrosa NC
Ref : Neurobiol Dis , 18 :176 , 2005
Abstract : Changes in signal transduction are implicated in neuronal responses to the Alzheimer's amyloid-beta-peptide (Abeta), which include neurotransmitter systems and pathways involved in the maintenance of the nervous system. We report here that a new bifunctional compound IBU-PO, which combines a non-steroidal anti-inflammatory drug (NSAID) (Ibuprofen) and a cholinesterase (ChE) inhibitor (Octyl-Pyridostigmine), is neuroprotective against Abeta-neurotoxicity, and its activity is associated to Wnt signaling components in rat hippocampal and mouse cortical neurons. IBU-PO (0.01-1 microM) inhibits glycogen-synthase-kinase-3beta (GSK-3beta) and stabilizes cytoplasmic beta-catenin reverting the silencing of the Wnt pathway caused by Abeta-toxicity and GSK-3beta overexpression. In addition, IBU-PO enhances, dose-dependently, the non-amyloidogenic amyloid precursor protein (APP) cleavage by increasing secreted APP and decreasing endogenous Abeta1-40 in rat hippocampal neurons.
ESTHER : Farias_2005_Neurobiol.Dis_18_176
PubMedSearch : Farias_2005_Neurobiol.Dis_18_176
PubMedID: 15649708

Title : Acetylcholinesterase-amyloid-beta-peptide interaction: effect of Congo Red and the role of the Wnt pathway - Inestrosa_2005_Curr.Alzheimer.Res_2_301
Author(s) : Inestrosa NC , Alvarez A , Dinamarca MC , Perez-Acle T , Colombres M
Ref : Curr Alzheimer Res , 2 :301 , 2005
Abstract : The cholinergic system impairment observed in Alzheimer's disease (AD) patients leads to the cognitive, global and behavioral dysfunction commonly associated with dementia. The only treatment for AD has been the use of inhibitors of acetylcholinesterase (AChE) (E.C. 3.1.1.7), which is one of the several proteins associated with amyloid plaque deposits. Recently, novel dual inhibitors of AChE have been developed that target both the active site of the enzyme as well as the peripheral anionic site (PAS). Such inhibitors prevent the aggregation of amyloid-beta-peptide (Abeta) into Alzheimer's fibrils. The incorporation of AChE, as a "chaperone" into amyloid aggregates results in the modification of the biochemical properties of the enzyme, including: sensitivity to low pH, inhibition at high substrate concentration, and increases of the Abeta neurotoxicity. Congo Red dye stabilizes the Abeta monomer, is able to inhibit oligomerization, and inhibits the binding of AChE to Abeta. However no effect of Congo Red on the binding of AChE to the Abeta preformed fibrils was observed. These studies suggest that different interactions between Abeta soluble-AChE and Abeta fibrils-AChE take place during the association between them. Docking studies were performed to evaluate the binding of Congo Red to Abeta in order to identify putative binding sites in the Abeta monomer that might interact with AChE. The binding site involves a region between residues 12 and 16. Finally, recent studies are consistent with the idea that a attenuating beta-catenin loss of function of Wnt signaling components may play a role in the progression of neurodegenerative disease, such as AD, providing a connection between AChE-Abeta neurotoxicity and the Wnt signal transduction pathway.
ESTHER : Inestrosa_2005_Curr.Alzheimer.Res_2_301
PubMedSearch : Inestrosa_2005_Curr.Alzheimer.Res_2_301
PubMedID: 15974895

Title : Is there a role for copper in neurodegenerative diseases? - Cerpa_2005_Mol.Aspects.Med_26_405
Author(s) : Cerpa W , Varela-Nallar L , Reyes AE , Minniti AN , Inestrosa NC
Ref : Mol Aspects Med , 26 :405 , 2005
Abstract : Copper is an essential metal in living organisms; thus, the maintenance of adequate copper levels is of vital importance and is highly regulated. Dysfunction of copper metabolism leading to its excess or deficiency results in severe ailments. Two examples of illnesses related to alterations in copper metabolism are Menkes and Wilson diseases. Several proteins are involved in the maintenance of copper homeostasis, including copper transporters and metal chaperones. In the last several years, the beta-amyloid-precursor protein (beta-APP) and the prion protein (PrP(C)), which are related to the neurodegenerative disorders Alzheimer and prion diseases respectively, have been associated with copper metabolism. Both proteins bind copper through copper-binding domains that also have been shown to reduce copper in vitro. Moreover, this ability to reduce copper is associated with a neuroprotective effect exerted by the copper-binding domain of both proteins against copper in vivo. In addition to a functional link between copper and beta-APP or PrP(C), evidence suggests that copper has a role in Alzheimer and prion diseases. Here, we review the evidence that supports both, the role of beta-APP and PrP(C), in copper metabolism and the putative role of copper in neurodegenerative diseases.
ESTHER : Cerpa_2005_Mol.Aspects.Med_26_405
PubMedSearch : Cerpa_2005_Mol.Aspects.Med_26_405
PubMedID: 16112188

Title : Blood cells cholinesterase activity in early stage Alzheimer's disease and vascular dementia - von Bernhardi_2005_Dement.Geriatr.Cogn.Disord_19_204
Author(s) : Von Bernhardi R , Alarcon R , Mezzano D , Fuentes P , Inestrosa NC
Ref : Dementia & Geriatric Cognitive Disorders , 19 :204 , 2005
Abstract : Blood acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities have been studied as markers for Alzheimer's disease (AD), but their usefulness as a disease marker is controversial. To determine cholinesterase (ChE) activity during AD progression and whether ChE changes associate to other dementias, ChE activity was measured in lymphocytes, erythrocytes and platelets. Subjects underwent extensive medical and neuropsychological examination. Both early-AD and AD patients had lower AChE activity in lymphocytes compared to control subjects (p < 0.0001). In contrast, erythrocyte AChE activity was higher in patients with vascular dementia (p = 0.004). Low ChE activity in lymphocytes was the best discriminator for AD. Because it was already low at very early stages of AD, ChE could be helpful as an early biomarker of differential diagnosis for the follow-up of patients during their early stages of cognitive impairment before a clinical dementia is established.
ESTHER : von Bernhardi_2005_Dement.Geriatr.Cogn.Disord_19_204
PubMedSearch : von Bernhardi_2005_Dement.Geriatr.Cogn.Disord_19_204
PubMedID: 15677868

Title : Copper brain homeostasis: role of amyloid precursor protein and prion protein - Inestrosa_2005_IUBMB.Life_57_645
Author(s) : Inestrosa NC , Cerpa W , Varela-Nallar L
Ref : IUBMB Life , 57 :645 , 2005
Abstract : The main proteins associated with Alzheimer's and prion diseases (amyloid precursor protein (APP) and prion protein (PrP(C)), respectively, have binding sites for copper and it has therefore been suggested that they play a role in copper metabolism. Here, we review evidence indicating that the copper binding domains (CuBD) of APP and PrP(C) are able to modulate the oxidation state of copper, and prevent neurotoxic effects and memory impairments induced by copper. Results with transgenic and other animal models have established the relation between these pathogenic proteins and copper. In particular, APP transgenic models, suggest a beneficial effect for copper in AD.
ESTHER : Inestrosa_2005_IUBMB.Life_57_645
PubMedSearch : Inestrosa_2005_IUBMB.Life_57_645
PubMedID: 16203684

Title : Structure and function of amyloid in Alzheimer's disease - Morgan_2004_Prog.Neurobiol_74_323
Author(s) : Morgan C , Colombres M , Nunez MT , Inestrosa NC
Ref : Prog Neurobiol , 74 :323 , 2004
Abstract : This review is focused on the structure and function of Alzheimer's amyloid deposits. Amyloid formation is a process in which normal well-folded cellular proteins undergo a self-assembly process that leads to the formation of large and ordered protein structures. Amyloid deposition, oligomerization, and higher order polymerization, and the structure adopted by these assemblies, as well as their functional relationship with cell biology are underscored. Numerous efforts have been directed to elucidate these issues and their relation with senile dementia. Significant advances made in the last decade in amyloid structure, dynamics and cell biology are summarized and discussed. The mechanism of amyloid neurotoxicity is discussed with emphasis on the Wnt signaling pathway. This review is focused on Alzheimer's amyloid fibrils in general and has been divided into two parts dealing with the structure and function of amyloid.
ESTHER : Morgan_2004_Prog.Neurobiol_74_323
PubMedSearch : Morgan_2004_Prog.Neurobiol_74_323
PubMedID: 15649580

Title : An overview of the current and novel drugs for Alzheimer's disease with particular reference to anti-cholinesterase compounds - Colombres_2004_Curr.Pharm.Des_10_3121
Author(s) : Colombres M , Sagal JP , Inestrosa NC
Ref : Curr Pharm Des , 10 :3121 , 2004
Abstract : Several cellular processes could be targeted if the complex nature of Alzheimer's disease (AD) was already understood. Most of AD treatments have been focused on the inhibition of acetylcholinesterase (AChE) in order to raise the levels of its substrate, i.e. the neurotransmitter acetylcholine (ACh), to augment cognitive functions of affected patients. Effectiveness in AChE inhibition and side-effect issues of clinical (tacrine, donepezil, galanthamine and rivastigmine) as well as of novel inhibitors is reviewed here. Novel design methods for the inhibition of AChE include the use of in silico tools to predict the interactions between AChE and the desired compound, both at the active site of the enzyme, responsible of hydrolysing ACh and with the peripheral anionic site (PAS), which has been described as a promoting agent of the amyloid beta-peptide (A beta) aggregation present in the senile plaques of the brain of AD individuals.
ESTHER : Colombres_2004_Curr.Pharm.Des_10_3121
PubMedSearch : Colombres_2004_Curr.Pharm.Des_10_3121
PubMedID: 15544502

Title : Poster (40) Acetylcholinesterase - amyloid beta-peptide interaction. -
Author(s) : De Ferrari GV , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :342 , 2004
PubMedID:

Title : Neurodegenerative processes in Alzheimer?s disease. -
Author(s) : Inestrosa NC , De Ferrari GV , Opazo C , Alvarez A
Ref : Cholinergic Mechanisms, CRC Press :363 , 2004
PubMedID:

Title : Poster (61) Nerve-induced muscle activity modulates cgrp effect on AChE expression in rat myotubes -
Author(s) : Aldunate R , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :353 , 2004
PubMedID:

Title : Poster (63) The association of acetylcholinesterase to amyloid-beta-peptide aggregates increases jt~ neurotoxicity -
Author(s) : Alvarez A , Godoy JA , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :354 , 2004
PubMedID:

Title : Poster (71) Acetylcholinesterase induces neuronal loss and spatial memory deficits in mammalian hippocampus -
Author(s) : Chacon MA , Reyes AE , Calderon R , Alvarez A , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :357 , 2004
PubMedID:

Title : Poster (77) Galanthamine inhibits the aggregation of the amyloid-beta-peptide stimulated by acetylcholinesterase in vitro. -
Author(s) : Dinamarca MC , Campos EO , Hancke JL , Rakonczay Z , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :361 , 2004
PubMedID:

Title : Signal transduction during amyloid-beta-peptide neurotoxicity: role in Alzheimer disease - Fuentealba_2004_Brain.Res.Brain.Res.Rev_47_275
Author(s) : Fuentealba RA , Farias G , Scheu J , Bronfman M , Marzolo MP , Inestrosa NC
Ref : Brain Research Brain Res Rev , 47 :275 , 2004
Abstract : Alzheimer's disease (AD) is a neurodegenerative disorder with progressive dementia accompanied by two main structural changes in the brain: intracellular protein deposits termed neurofibrillary tangles (NFT) and extracellular amyloid protein deposits surrounded by dystrophic neurites that constitutes the senile plaques. Currently, it is widely accepted that amyloid beta-peptide (A beta) metabolism disbalance is crucial for AD progression. A beta deposition may be enhanced by molecular chaperones, including metals like copper and proteins like acetylcholinesterase (AChE). At the neuronal level, several AD-related proteins interact with transducers of the Wnt/beta-catenin signaling pathway, including beta-catenin and glycogen synthase kinase 3 beta (GSK-3 beta) and both in vitro and in vivo studies suggest that Wnt/beta-catenin signaling is a target for A beta toxicity. Accordingly, activation of this signaling by lithium or Wnt ligands in AD-experimental animal models or in primary hippocampal neurons attenuate A beta neurotoxicity by recovering beta-catenin levels and Wnt-target gene expression of survival genes such as bcl-2. On the other hand, peroxisomal proliferator-activated receptor gamma (PPAR gamma) and muscarinic acetylcholine receptor (mAChR) agonists also activate Wnt/beta-catenin signaling and they have neuroprotective effects on hippocampal neurons. Our studies are consistent with the idea that a sustained loss of function of Wnt signaling components would trigger a series of events, determining the onset and development of AD and that modulation of this pathway through the activation of cross-talking signaling cascades should be considered as a possible therapeutic strategy for AD treatment.
ESTHER : Fuentealba_2004_Brain.Res.Brain.Res.Rev_47_275
PubMedSearch : Fuentealba_2004_Brain.Res.Brain.Res.Rev_47_275
PubMedID: 15572177

Title : Nerve-induced muscle activity modulates CGRP effect on AChE expression in rat myotubes -
Author(s) : Aldunate R , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :31 , 2004
PubMedID:

Title : Acetylcholinesterase (AChE)--amyloid-beta-peptide complexes in Alzheimer's disease. the Wnt signaling pathway - Inestrosa_2004_Curr.Alzheimer.Res_1_249
Author(s) : Inestrosa NC , Urra S , Colombres M
Ref : Curr Alzheimer Res , 1 :249 , 2004
Abstract : Alzheimer's disease (AD) is characterized by selective neuronal cell death, which is probably caused by amyloid beta-peptide (Abeta) oligomers and fibrils. We have found that acetylcholinesterase (AChE), a senile plaque component, increases amyloid fibril assembly with the formation of highly toxic complexes (Abeta-AChE). The neurotoxic effect induced by Abeta-AChE complexes was higher than that induced by the Abeta peptide alone as shown both in vitro (hippocampal neurons) and in vivo (rats injected with Abeta peptide in the dorsal hippocampus). Interestingly, treatment with Abeta-AChE complexes decreases the cytoplasmic beta-catenin level, a key component of Wnt signaling. Conversely, the activation of this signaling pathway by Wnt-3a promotes neuronal survival and rescues changes in Wnt components (activation or subcellular localization). Moreover Frzb-1, a Wnt antagonist reverses the Wnt-3a neuroprotection effect against Abeta neurotoxicity. Compounds that mimic the Wnt signaling or modulate the cross-talking with this pathway could be used as neuroprotective agents for therapeutic strategies in AD patients.
ESTHER : Inestrosa_2004_Curr.Alzheimer.Res_1_249
PubMedSearch : Inestrosa_2004_Curr.Alzheimer.Res_1_249
PubMedID: 15975054

Title : Poster (80) The anti-inflammatory-cholinergic bifunctional compound ibu-po protects at sub-micromolar levels rat hippocampal cells from a beta-induced apoptosis and beta-catenin depletion -
Author(s) : Godoy JA , Adani R , Meshulam H , Inestrosa NC , Amitai G
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :363 , 2004
PubMedID:

Title : Neurodegenerative processes in Alzheimer's disease: Role of A-beta-AChE complexes and Wnt signaling -
Author(s) : Inestrosa NC , Colombres M , De Ferrari GV
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :95 , 2004
PubMedID:

Title : Stepwise construction of triple-helical heparin binding sites using peptide models - Doss-Pepe_2004_Biochim.Biophys.Acta_1698_187
Author(s) : Doss-Pepe E , Deprez P , Silva T , Inestrosa NC , Kirkpatrick A , Ramshaw JA , Brodsky B
Ref : Biochimica & Biophysica Acta , 1698 :187 , 2004
Abstract : The specific localization of the asymmetric form of acetylcholinesterase (AChE) in neuromuscular junctions results from the interaction of its collagen-like tail with heparan sulfate proteoglycans in the synaptic basal lamina. This interaction involves two heparin binding consensus sequences of the form XBBXB, where B is a basic residue, located in the triple-helical collagen tail: GRKGR for the N-terminal site and GKRGK for the C-terminal site. To explore the basis of the higher heparin affinity seen for the C-terminal site vs. the N-terminal site, two homologous series of (Gly-Xaa-Yaa)(8) peptides were constructed to model these triple-helical binding sites. Individual tripeptide units from each heparin binding site were introduced in a stepwise fashion into a Gly-Pro-Hyp framework, until the consensus sequence and its surrounding triplets were recreated. As each additional triplet from the binding site is inserted to replace a host Gly-Pro-Hyp triplet, the triple-helix stability decreases, and the drop in thermal stability is close to that expected if each Gly-X-Y triplet contributed independently to global stability. CD spectroscopy and calorimetry show the stability of these AChE model peptides is increased by addition of heparin, confirming binding to heparin, and the lack of significant enthalpy change indicates the binding is largely electrostatic in nature. Displacement assays measure the strength of the peptide-heparin interaction, and indicate an inverse correlation between the peptide ability to bind heparin and its thermal stability. The model peptides for the C-terminal binding site show a greater heparin affinity than the peptide models for the N-terminal binding site only when residues surrounding the consensus sequence are included.
ESTHER : Doss-Pepe_2004_Biochim.Biophys.Acta_1698_187
PubMedSearch : Doss-Pepe_2004_Biochim.Biophys.Acta_1698_187
PubMedID: 15134651

Title : Effects of intrahippocampal injection of acetylcholinesterase-A-beta complexes and AChE alone: Analysis of neuropathological changes and spatial learning acquisition -
Author(s) : Chacon MA , Reyes AE , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :119 , 2004
PubMedID:

Title : Poster (92) Acetylcholinesterase stabilizes amyloid fibrils against disassembly induced by laminin -
Author(s) : Morgan C , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :369 , 2004
PubMedID:

Title : The anti-inflammatory bifunctional compound IBU-PO protects rat hippocampal neurons from A-beta-induced cytotoxicity and beta-catenin depletion -
Author(s) : Godoy JA , Adani R , Meshulam H , Inestrosa NC , Amitai G
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :135 , 2004
PubMedID:

Title : Acetylcholinesterase stabilizes beta-amyloid fibrils against disassembly induced by laminin -
Author(s) : Morgan C , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :141 , 2004
PubMedID:

Title : The association of AChE to A-beta peptide aggregates increases its neurotoxicity -
Author(s) : Alvarez A , Godoy JA , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :147 , 2004
PubMedID:

Title : Increased detection of amyloid precursor protein in astrocytes exposed to acetylcholinesterase in culture -
Author(s) : Von Bernhardi R , Ramirez G , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :153 , 2004
PubMedID:

Title : Decreased cholinesterase activity in blood cells of Alzheimer's disease patients -
Author(s) : Von Bernhardi R , Alarcon R , Mezzano D , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :159 , 2004
PubMedID:

Title : Poster (102) Blood cells cholinesterase activity and dementia: decreased activity is established from early stages in alzheimer's disease and is common to various organic dementias -
Author(s) : Von Bernhardi R , Alarcon R , Mezzano D , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :373 , 2004
PubMedID:

Title : Poster (103) Acetylcholinesterase induces the expression of the beta-amyloid precursor protein in astrocytes and activates glial cells in culture -
Author(s) : Von Bernhardi R , Ramirez G , Inestrosa NC
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :374 , 2004
PubMedID:

Title : Structural and functional organization of synaptic acetylcholinesterase - Aldunate_2004_Brain.Res.Brain.Res.Rev_47_96
Author(s) : Aldunate R , Casar JC , Brandan E , Inestrosa NC
Ref : Brain Research Brain Res Rev , 47 :96 , 2004
Abstract : The expression of the synaptic asymmetric form of the enzyme acetylcholinesterase (AChE) depends of two different genes: the gene that encodes for the catalytic subunit and the gene that encodes for the collagenic tail, ColQ. Asymmetric AChE is specifically localized to the basal lamina at the neuromuscular junction (NMJ). This highly organized distribution pattern suggests the existence of one or more specific binding sites in ColQ required for its anchorage to the synaptic basal lamina. Recent evidence support this notion: first, the presence of two heparin-binding domains in ColQ that interact with heparan sulfate proteoglycans (HSPGs) at the synaptic basal lamina; and second, a knockout mouse for perlecan, a HSPG concentrated in nerve-muscle contact, in which absence of asymmetric AChE at the NMJ is observed. The physiological importance of collagen-tailed AChE form in skeletal muscle has been illustrated by the identification of several mutations in the ColQ gene. These mutations determine end-plate acetylcholinesterase deficiency and induce one type of synaptic functional disorders observed in Congenital Myasthenic Syndromes (CMSs).
ESTHER : Aldunate_2004_Brain.Res.Brain.Res.Rev_47_96
PubMedSearch : Aldunate_2004_Brain.Res.Brain.Res.Rev_47_96
PubMedID: 15572165

Title : Acetylcholinesterase-Abeta complexes are more toxic than Abeta fibrils in rat hippocampus: effect on rat beta-amyloid aggregation, laminin expression, reactive astrocytosis, and neuronal cell loss - Reyes_2004_Am.J.Pathol_164_2163
Author(s) : Reyes AE , Chacon MA , Dinamarca MC , Cerpa W , Morgan C , Inestrosa NC
Ref : American Journal of Pathology , 164 :2163 , 2004
Abstract : Neuropathological changes generated by human amyloid-beta peptide (Abeta) fibrils and Abeta-acetylcholinesterase (Abeta-AChE) complexes were compared in rat hippocampus in vivo. Results showed that Abeta-AChE complexes trigger a more dramatic response in situ than Abeta fibrils alone as characterized by the following features observed 8 weeks after treatment: 1). amyloid deposits were larger than those produced in the absence of AChE. In fact, AChE strongly stimulates rat Abeta aggregation in vitro as shown by turbidity measurements, Congo Red binding, as well as electron microscopy, suggesting that Abeta-AChE deposits observed in vivo probably recruited endogenous Abeta peptide; 2). the appearance of laminin expressing neurons surrounding Abeta-AChE deposits (such deposits are resistant to disaggregation by laminin in vitro); 3). an extensive astrocytosis revealed by both glial fibrillary acidic protein immunoreactivity and number counting of reactive hypertrophic astrocytes; and 4). a stronger neuronal cell loss in comparison with Abeta-injected animals. We conclude that the hippocampal injection of Abeta-AChE complexes results in the appearance of some features reminiscent of Alzheimer-like lesions in rat brain. Our studies are consistent with the notion that Abeta-AChE complexes are more toxic than Abeta fibrils and that AChE triggered some of the neurodegenerative changes observed in Alzheimer's disease brains.
ESTHER : Reyes_2004_Am.J.Pathol_164_2163
PubMedSearch : Reyes_2004_Am.J.Pathol_164_2163
PubMedID: 15161650

Title : Two different heparin-binding domains in the triple-helical domain of ColQ, the collagen tail subunit of synaptic acetylcholinesterase - Deprez_2003_J.Biol.Chem_278_23233
Author(s) : Deprez P , Inestrosa NC , Krejci E
Ref : Journal of Biological Chemistry , 278 :23233 , 2003
Abstract : ColQ, the collagen tail subunit of asymmetric acetylcholinesterase, is responsible for anchoring the enzyme at the vertebrate synaptic basal lamina by interacting with heparan sulfate proteoglycans. To get insights about this function, the interaction of ColQ with heparin was analyzed. For this, heparin affinity chromatography of the complete oligomeric enzyme carrying different mutations in ColQ was performed. Results demonstrate that only the two predicted heparin-binding domains present in the collagen domain of ColQ are responsible for heparin interaction. Despite their similarity in basic charge distribution, each heparin-binding domain had different affinity for heparin. This difference is not solely determined by the number or nature of the basic residues conforming each site, but rather depends critically on local structural features of the triple helix, which can be influenced even by distant regions within ColQ. Thus, ColQ possesses two heparin-binding domains with different properties that may have non-redundant functions. We hypothesize that these binding sites coordinate acetylcholinesterase positioning within the organized architecture of the neuromuscular junction basal lamina.
ESTHER : Deprez_2003_J.Biol.Chem_278_23233
PubMedSearch : Deprez_2003_J.Biol.Chem_278_23233
PubMedID: 12684510

Title : Acetylcholinesterase induces neuronal cell loss, astrocyte hypertrophy and behavioral deficits in mammalian hippocampus - Chacon_2003_J.Neurochem_87_195
Author(s) : Chacon MA , Reyes AE , Inestrosa NC
Ref : Journal of Neurochemistry , 87 :195 , 2003
Abstract : Previous studies have demonstrated that acetylcholinesterase (AChE) promotes the assembly of amyloid-beta-peptides into neurotoxic amyloid fibrils and is toxic for chick retina neuronal cultures and neuroblastoma cells. Moreover, AChE is present in senile plaques in Alzheimer's disease (AD) brains. Here we have studied the effect of AChE on astrocytes and hippocampal neurons in vivo. Morphological as well as behavioral disturbances were analyzed after intrahippocampal injection of AChE. Rats were trained in the Morris water maze and assayed for behavioral parameters. Neuronal cell loss was found in the upper leaf of the dentate gyrus in rats injected with AChE in comparison with control animals. Glial fibrillary acidic protein immunoreactivity showed astrocytic hypertrophy and the magnitude of the response was associated with neuronal cell loss. Behavioral results show that injection of AChE produces cognitive impairment demonstrated by an altered water maze performance including (i) a higher escape latency score, (ii) a decreased spatial acuity and (iii) a shorter time of swimming in the platform quadrant. These findings indicate that a local increment in neuronal AChE concentration at the mammalian hippocampus, such as those present in amyloid deposits, may play a role in triggering neuropathological and behavioral changes such as those observed in AD brains.
ESTHER : Chacon_2003_J.Neurochem_87_195
PubMedSearch : Chacon_2003_J.Neurochem_87_195
PubMedID: 12969266

Title : Acetylcholinesterase induces the expression of the beta-amyloid precursor protein in glia and activates glial cells in culture - von Bernhardi_2003_Neurobiol.Dis_14_447
Author(s) : Von Bernhardi R , Ramirez G , De Ferrari GV , Inestrosa NC
Ref : Neurobiol Dis , 14 :447 , 2003
Abstract : Acetylcholinesterase (AChE) activities in CNS physiopathology are increasingly diverse and range from neuritogenesis, through synaptogenesis, to enhancement of amyloid fiber assembly. In Alzheimer's disease, senile plaques and neurodegeneration specially affect regions enriched for cholinergic synapses. In this study we show an effect of AChE that could contribute to the increased deposition of Abeta in certain regions. Affinity-purified AChE induced the expression of amyloid-beta-precursor protein (beta-APP) in glial cells in a concentration-dependent manner up to 5 nM. In glia, AChE also increased inducible nitric oxide synthase (iNOS) assessed by immunocytochemistry and decreased reductive metabolism as evidence of cell activation. AChE could increase the expression of beta-APP in astrocytes and microglia as result of the activation of glial cells. As a whole, we found that AChE has additional effects that could result in an increased synthesis of Abeta, both by increasing beta-APP expression of astrocytes and by further activating glial cells.
ESTHER : von Bernhardi_2003_Neurobiol.Dis_14_447
PubMedSearch : von Bernhardi_2003_Neurobiol.Dis_14_447
PubMedID: 14678761

Title : Vitamin E but not 17beta-estradiol protects against vascular toxicity induced by beta-amyloid wild type and the Dutch amyloid variant - Munoz_2002_J.Neurosci_22_3081
Author(s) : Munoz FJ , Opazo C , Gil-Gomez G , Tapia G , Fernandez V , Valverde MA , Inestrosa NC
Ref : Journal of Neuroscience , 22 :3081 , 2002
Abstract : Amyloid beta-peptide (Abeta) fibril deposition on cerebral vessels produces cerebral amyloid angiopathy that appears in the majority of Alzheimer's disease patients. An early onset of a cerebral amyloid angiopathy variant called hereditary cerebral hemorrhage with amyloidosis of the Dutch type is caused by a point mutation in Abeta yielding Abeta(Glu22-->Gln). The present study addresses the effect of amyloid fibrils from both wild-type and mutated Abeta on vascular cells, as well as the putative protective role of antioxidants on amyloid angiopathy. For this purpose, we studied the cytotoxicity induced by Abeta(1-40 Glu22-->Gln) and Abeta(1-40 wild-type) fibrils on human venule endothelial cells and rat aorta smooth muscle cells. We observed that Abeta(Glu22-->Gln) fibrils are more toxic for vascular cells than the wild-type fibrils. We also evaluated the cytotoxicity of Abeta fibrils bound with acetylcholinesterase (AChE), a common component of amyloid deposits. Abeta(1-40 wild-type)-AChE fibrillar complexes, similar to neuronal cells, resulted in an increased toxicity on vascular cells. Previous reports showing that antioxidants are able to reduce the toxicity of Abeta fibrils on neuronal cells prompted us to test the effect of vitamin E, vitamin C, and 17beta-estradiol on vascular damage induced by Abeta(wild-type) and Abeta(Glu22-->Gln). Our data indicate that vitamin E attenuated significantly the Abeta-mediated cytotoxicity on vascular cells, although 17beta-estradiol and vitamin C failed to inhibit the cytotoxicity induced by Abeta fibrils.
ESTHER : Munoz_2002_J.Neurosci_22_3081
PubMedSearch : Munoz_2002_J.Neurosci_22_3081
PubMedID: 11943811

Title : A Structural Motif of Acetylcholinesterase That Promotes Amyloid beta-Peptide Fibril Formation - De Ferrari_2001_Biochemistry_40_10447
Author(s) : De Ferrari GV , Canales MA , Shin I , Weiner L , Silman I , Inestrosa NC
Ref : Biochemistry , 40 :10447 , 2001
Abstract : Acetylcholinesterase (AChE) has been found to be associated with the core of senile plaques. We have shown that AChE interacts with the amyloid beta-peptide (Abeta) and promotes amyloid fibril formation by a hydrophobic environment close to the peripheral anionic binding site (PAS) of the enzyme. Here we present evidence for the structural motif of AChE involved in this interaction. First, we modeled the docking of Abeta onto the structure of Torpedo californica AChE, and identified four potential sites for AChE-Abeta complex formation. One of these, Site I, spans a major hydrophobic sequence exposed on the surface of AChE, which had been previously shown to interact with liposomes [Shin et al. (1996) Protein Sci. 5, 42-51]. Second, we examined several AChE-derived peptides and found that a synthetic 35-residue peptide corresponding to the above hydrophobic sequence was able to promote amyloid formation. We also studied the ability to promote amyloid formation of two synthetic 24-residue peptides derived from the sequence of a Omega-loop, which has been suggested as an AChE-Abeta interacting motif. Kinetic analyses indicate that only the 35-residue hydrophobic peptide mimics the effect of intact AChE on amyloid formation. Moreover, RP-HPLC analysis revealed that the 35-residue peptide was incorporated into the growing Abeta-fibrils. Finally, fluorescence binding studies showed that this peptide binds Abeta with a K(d) = 184 microM, independent of salt concentration, indicating that the interaction is primarily hydrophobic. Our results indicate that the homologous human AChE motif is capable of accelerating Abeta fibrillogenesis.
ESTHER : De Ferrari_2001_Biochemistry_40_10447
PubMedSearch : De Ferrari_2001_Biochemistry_40_10447
PubMedID: 11523986

Title : Thioflavin T is a fluorescent probe of the acetylcholinesterase peripheral site that reveals conformational interactions between the peripheral and the acylation sites - De Ferrari_2001_J.Biol.Chem_276_23282
Author(s) : De Ferrari GV , Mallender WD , Inestrosa NC , Rosenberry TL
Ref : Journal of Biological Chemistry , 276 :23282 , 2001
Abstract : Three-dimensional structures of acetylcholinesterase (AChE) reveal a narrow and deep active site gorge with two sites of ligand binding, an acylation site at the base of the gorge, and a peripheral site near the gorge entrance. Recent studies have shown that the peripheral site contributes to catalytic efficiency by transiently binding substrates on their way to the acylation site, but the question of whether the peripheral site makes other contributions to the catalytic process remains open. A possible role for ligand binding to the peripheral site that has long been considered is the initiation of a conformational change that is transmitted allosterically to the acylation site to alter catalysis. However, evidence for conformational interactions between these sites has been difficult to obtain. Here we report that thioflavin T, a fluorophore widely used to detect amyloid structure in proteins, binds selectively to the AChE peripheral site with an equilibrium dissociation constant of 1.0 microm. The fluorescence of the bound thioflavin T is increased more than 1000-fold over that of unbound thioflavin T, the greatest enhancement of fluorescence for the binding of a fluorophore to AChE yet observed. Furthermore, when the acylation site ligands edrophonium or m-(N, N,N-trimethylammonio)trifluoroacetophenone form ternary complexes with AChE and thioflavin T, the fluorescence is quenched by factors of 2.7-4.2. The observation of this partial quenching of thioflavin T fluorescence is a major advance in the study of AChE for two reasons. First, it allows thioflavin T to be used as a reporter for ligand reactions at the acylation site. Second, it indicates that ligand binding to the acylation site initiates a change in the local AChE conformation at the peripheral site that quenches the fluorescence of bound thioflavin T. The data provide strong evidence in support of a conformational interaction between the two AChE sites.
ESTHER : De Ferrari_2001_J.Biol.Chem_276_23282
PubMedSearch : De Ferrari_2001_J.Biol.Chem_276_23282
PubMedID: 11313335

Title : Interaction of collagen-like peptide models of asymmetric acetylcholinesterase with glycosaminoglycans: spectroscopic studies of conformational changes and stability - Doss-Pepe_2000_Biochemistry_39_14884
Author(s) : Doss-Pepe E , Deprez P , Inestrosa NC , Brodsky B
Ref : Biochemistry , 39 :14884 , 2000
Abstract : The effect of heparin on the conformation and stability of triple-helical peptide models of the collagen tail of asymmetric acetylcholinesterase expands our understanding of heparin interactions with proteins and presents an opportunity for clarifying the nature of binding of ligands to collagen triple-helix domains. Within the collagen tail of AChE, there are two consensus sequences for heparin binding of the form BBXB, surrounded by additional basic residues. Circular dichroism studies were used to determine the effect of the addition of increasing concentrations of heparin on triple-helical peptide models for the heparin binding domains, including peptides in which the basic residues within and surrounding the consensus sequence were replaced by alanine residues. The addition of heparin caused an increased triple-helix content with saturation properties for the peptide modeling the C-terminal site, while precipitation, with no increased helix content resulted from heparin addition to the peptide modeling the N-terminal site. The results suggest that the two binding sites with a similar triple-helical conformation have distinctive ways of interacting with heparin, which must relate to small differences in the consensus sequence (GRKGR vs GKRGK) and in the surrounding basic residues. Addition of heparin increased the thermal stability of all peptides containing the consensus sequence. Heparan sulfate produced conformational and stabilization effects similar to those of heparin, while chondroitin sulfate led to a cloudy solution, loss of circular dichroism signal, and a smaller increase in thermal stability. Thus, specificity in both the sequence of the triple helix and the type of glycosaminoglycan is required for this interaction.
ESTHER : Doss-Pepe_2000_Biochemistry_39_14884
PubMedSearch : Doss-Pepe_2000_Biochemistry_39_14884
PubMedID: 11101304

Title : Acetylcholinesterase-amyloid-beta-peptide interaction and Wnt signaling involvement in Abeta neurotoxicity - Inestrosa_2000_Acta.Neurol.Scand.Suppl_176_53
Author(s) : Inestrosa NC , Alvarez A , Godoy J , Reyes A , De Ferrari GV
Ref : Acta Neurologica Scandinavica Supplementum , 176 :53 , 2000
Abstract : Previous studies have indicated that acetylcholinesterase (AChE) promotes amyloid-beta-peptide (Abeta) fibril formation and AChE-Abeta complexes increase Abeta-dependent neurotoxicity. Here we present evidence for the: i) identification of the AChE motif that promotes amyloid formation, ii) in vivo effect of AChE on brain plaque formation, and iii) connection between AChE-Abeta neurotoxicity and the Wnt signal transduction pathway. Computer modeling, stereotaxic infusions and cell biological techniques were used to study the above problems. Results indicated that a 3.4 kDa AChE peptide promotes Abeta fibril formation. AChE infusion into rat hippocampus determines the appearance of anti-Abeta and thioflavine-S positive plaques, and AChE-Abeta toxicity on hippocampal cultures was blocked by lithium, an activator of the Wnt cascade. We suggest that AChE-Abeta/Abeta dependent neurotoxicity may result in loss of function of Wnt signaling components, and open the possibility that lithium may be considered as a candidate for therapeutic intervention in Alzheimer's disease pathology.
ESTHER : Inestrosa_2000_Acta.Neurol.Scand.Suppl_176_53
PubMedSearch : Inestrosa_2000_Acta.Neurol.Scand.Suppl_176_53
PubMedID: 11261806

Title : Interaction of the collagen-like tail of asymmetric acetylcholinesterase with heparin depends on triple-helical conformation, sequence and stability - Deprez_2000_Biochem.J_350 Pt 1_283
Author(s) : Deprez P , Doss-Pepe E , Brodsky B , Inestrosa NC
Ref : Biochemical Journal , 350 Pt 1 :283 , 2000
Abstract : The collagen-like tail of asymmetric acetylcholinesterase (AChE) contains two heparin-binding domains (HBDs) that interact with heparan sulphate proteoglycans, determining the anchoring of the enzyme at the basal lamina and its specific localization at the neuromuscular junction. Both HBDs are characterized by a cluster of basic residues containing a core with the BBXB consensus sequence (where B represents a basic residue and X a non-basic residue). To study the interaction of such HBDs with heparin we have used synthetic peptides to model the N-terminal and C-terminal sites. CD spectroscopy showed that all peptides are triple-helical at low temperatures, and undergo trimer-to-monomer transitions. Displacement assays of asymmetric AChE bound to heparin were performed using the peptides in both monomeric and triple-helical states. In the monomeric conformation, all the peptides were able to displace low levels of AChE depending on the basic charge content. In the triple-helical conformation, peptides containing the consensus sequence showed a large increase in the ability to displace bound AChE. Results suggest that the specific binding of the collagen-like-tail peptides to heparin depends both on the presence of the core sequence and on the triple-helical conformation. Moreover, BBXB-containing peptides that are less stable are more effective in displacing AChE, suggesting that the interaction region needs a significant amount of structural flexibility to better accommodate the ligand.
ESTHER : Deprez_2000_Biochem.J_350 Pt 1_283
PubMedSearch : Deprez_2000_Biochem.J_350 Pt 1_283
PubMedID: 10926855

Title : Molecular modeling of the collagen-like tail of asymmetric acetylcholinesterase - Deprez_2000_Protein.Eng_13_27
Author(s) : Deprez P , Inestrosa NC
Ref : Protein Engineering , 13 :27 , 2000
Abstract : The asymmetric form of acetylcholinesterase comprises three catalytic tetramers attached to ColQ, a collagen-like tail responsible for the anchorage of the enzyme to the synaptic basal lamina. ColQ is composed of an N-terminal domain which interacts with the catalytic subunits of the enzyme, a central collagen-like domain and a C-terminal globular domain. In particular, the collagen-like domain of ColQ contains two heparin-binding domains which interact with heparan sulfate proteoglycans in the basal lamina. A three-dimensional model of the collagen-like domain of the tail of asymmetric acetylcholinesterase was constructed. The model presents an undulated shape that results from the presence of a substitution and an insertion in the Gly-X-Y repeating pattern, as well as from low imino-acid regions. Moreover, this model permits the analysis of interactions between the heparin-binding domains of ColQ and heparin, and could also prove useful in the prediction of interaction domains with other putative basal lamina receptors.
ESTHER : Deprez_2000_Protein.Eng_13_27
PubMedSearch : Deprez_2000_Protein.Eng_13_27
PubMedID: 10679527

Title : The role of oxidative stress in the toxicity induced by amyloid beta-peptide in Alzheimer's disease - Miranda_2000_Prog.Neurobiol_62_633
Author(s) : Miranda S , Opazo C , Larrondo LF , Munoz FJ , Ruiz F , Leighton F , Inestrosa NC
Ref : Prog Neurobiol , 62 :633 , 2000
Abstract : One of the theories involved in the etiology of Alzheimer's disease (AD) is the oxidative stress hypothesis. The amyloid beta-peptide (A beta), a hallmark in the pathogenesis of AD and the main component of senile plaques, generates free radicals in a metal-catalyzed reaction inducing neuronal cell death by a reactive oxygen species mediated process which damage neuronal membrane lipids, proteins and nucleic acids. Therefore, the interest in the protective role of different antioxidants in AD such as vitamin E, melatonin and estrogens is growing up. In this review we summarize data that support the involvement of oxidative stress as an active factor in A beta-mediated neuropathology, by triggering or facilitating neurodegeneration, through a wide range of molecular events that disturb neuronal cell homeostasis.
ESTHER : Miranda_2000_Prog.Neurobiol_62_633
PubMedSearch : Miranda_2000_Prog.Neurobiol_62_633
PubMedID: 10880853

Title : Peripheral binding site is involved in the neurotrophic activity of acetylcholinesterase - Munoz_1999_Neuroreport_10_3621
Author(s) : Munoz FJ , Aldunate R , Inestrosa NC
Ref : Neuroreport , 10 :3621 , 1999
Abstract : Acetylcholinesterase (AChE) catalyses the hydrolysis of the neurotransmitter acetylcholine and it has been implicated in several non-cholinergic actions, including neurite outgrowth and amyloid formation. We have studied the trophic function of brain AChE on neuronal cell metabolism and proliferation as well as the enzyme domain involved in such effects. Low AChE concentrations (0.1-2.5 nM) stimulated neurite outgrowth and induced cell proliferation as measured by MTT reduction and [3H]thymidine incorporation. The action of AChE was not affected by edrophonium and tacrine both active site inhibitors, but it was abolished by propidium and gallamine, two peripheral anionic binding site (PAS) ligands. We conclude that the PAS domain of AChE is involved in the neurotrophic activity of the enzyme.
ESTHER : Munoz_1999_Neuroreport_10_3621
PubMedSearch : Munoz_1999_Neuroreport_10_3621
PubMedID: 10619655

Title : Neurotoxicity of acetylcholinesterase amyloid beta-peptide aggregates is dependent on the type of Abeta peptide and the AChE concentration present in the complexes - Munoz_1999_FEBS.Lett_450_205
Author(s) : Munoz FJ , Inestrosa NC
Ref : FEBS Letters , 450 :205 , 1999
Abstract : Alzheimer's disease (AD) is a neurodegenerative disorder whose hallmark is the presence of senile plaques and neurofibrillary tangles. Senile plaques are mainly composed of amyloid beta-peptide (Abeta) fibrils and several proteins including acetylcholinesterase (AChE). AChE has been previously shown to stimulate the aggregation of Abeta1-40 into amyloid fibrils. In the present work, the neurotoxicity of different amyloid aggregates formed in the absence or presence of AChE was evaluated in rat pheochromocytoma PC12 cells. Stable AChE-Abeta complexes were found to be more toxic than those formed without the enzyme, for Abeta1-40 and Abeta1-42, but not for amyloid fibrils formed with AbetaVal18-Ala, a synthetic variant of the Abeta1-40 peptide. Of all the AChE-Abeta complexes tested the one containing the Abeta1-40 peptide was the most toxic. When increasing concentrations of AChE were used to aggregate the Abeta1-40 peptide, the neurotoxicity of the complexes increased as a function of the amount of enzyme bound to each complex. Our results show that AChE-Abeta1-40 aggregates are more toxic than those of AChE-Abeta1-42 and that the neurotoxicity depends on the amount of AChE bound to the complexes, suggesting that AChE may play a key role in the neurodegeneration observed in Alzheimer brain.
ESTHER : Munoz_1999_FEBS.Lett_450_205
PubMedSearch : Munoz_1999_FEBS.Lett_450_205
PubMedID: 10359075

Title : PC12 and neuro 2a cells have different susceptibilities to acetylcholinesterase-amyloid complexes, amyloid25-35 fragment, glutamate, and hydrogen peroxide - Calderon_1999_J.Neurosci.Res_56_620
Author(s) : Calderon FH , Bonnefont A , Munoz FJ , Fernandez V , Videla LA , Inestrosa NC
Ref : Journal of Neuroscience Research , 56 :620 , 1999
Abstract : This work addresses the differential effects of several oxidative insults on two neuronal cell lines, PC12 and Neuro 2a cells, extensively used as neuronal models in vitro. We measured cellular damage using the cytotoxic assays for MTT reduction and LDH release and found that acetylcholinesterase (AChE)-amyloid-beta-peptide (Abeta) complexes, Abeta25-35 fragment, glutamate and H2O2 were over 200-fold more toxic to PC12 than to Neuro 2a cells. 17alpha and 17beta estradiol were able to protect both cell types from damage caused by H2O2 or glutamate. By contrast, other insults not related to oxidative stress, such as those caused by the nonionic detergent Triton X-100 and serum deprivation, induced a similar level of damage in both PC12 and Neuro 2a cells. Considering that the Abeta peptide, H2O2 and glutamate are cellular insults that cause an increase in reactive oxygen species (ROS), the intracellular levels of the antioxidant compound, glutathione were verified. Neuro 2a cells were found to have 4- to 5-fold more glutathione than PC12 cells. Our results suggest that Neuro 2a cells are less susceptible to exposure to AChE-Abeta complexes, Abeta25-35 fragment, glutamate and H2O2 than PC12 cells, due to higher intracellular levels of antioxidant defense factors.
ESTHER : Calderon_1999_J.Neurosci.Res_56_620
PubMedSearch : Calderon_1999_J.Neurosci.Res_56_620
PubMedID: 10374817

Title : Mannose receptor is present in a functional state in rat microglial cells - Marzolo_1999_J.Neurosci.Res_58_387
Author(s) : Marzolo MP , Von Bernhardi R , Inestrosa NC
Ref : Journal of Neuroscience Research , 58 :387 , 1999
Abstract : We studied the expression of the mannose receptor (ManR) in rat microglial cells. Microglial cells are the central nervous system resident macrophages, key participants of the innate immune response. ManR is a differentiation marker and a relevant glycoprotein for the phagocytic and endocytic function of macrophages. Because there is evidence suggesting that ManR could mediate some of the nonenzymatic effects of acetilcholinesterase (AchE) and the enzyme seems to be involved in Alzheimer's disease (AD), we looked for ManR in microglia, evaluating the functionality of the receptor. We isolated microglial cells from the brain of 2-day-old neonatal rats. Microglial cells, identified by their specific staining with the lectin Griffonia simplicifolia, expressed ManR, being detected by immunocytochemistry, Western blot, and immunoprecipitation. Microglial ManR was downregulated by lipopolysaccharide (LPS) and upregulated by dexamethasone, as described for peripheral macrophages. Microglial ManR was functional and able to internalize horseradish peroxidase (HRP), a known ManR ligand, in a mannan-inhibitable manner. The presence of a functional ManR in microglia opens the possibility that ManR could participate in multiple physiologic and pathologic conditions in the central nervous system (CNS), including inflammation, ischaemia, and neurodegenerative diseases such as AD.
ESTHER : Marzolo_1999_J.Neurosci.Res_58_387
PubMedSearch : Marzolo_1999_J.Neurosci.Res_58_387
PubMedID: 10518112

Title : Crosslinking of amyloid-beta peptide to brain acetylcholinesterase - Opazo_1998_Mol.Chem.Neuropathol_33_39
Author(s) : Opazo C , Inestrosa NC
Ref : Molecular & Chemical Neuropathology , 33 :39 , 1998
Abstract : Acetylcholinesterase (AChE) is the enzyme responsible for the hydrolysis of the neurotransmitter acetylcholine in the central nervous system. Recently, we have found that AChE promotes the assembly of amyloid-beta peptides (A beta) into Alzheimer fibrils. The action of AChE on the state of aggregation of the A beta peptide supposes a near neighbor relationship between these two molecules. In the present work, we have studied A beta-AChE interactions using the crosslinker reagent disuccinimidyl suberate (DSS), in the presence of [125I]-A beta peptide. The A beta-AChE complexes formed by crosslinkage were then analyzed by SDS-PAGE and autoradiography. We observed the formation of [125I] A beta-labeled complexes of 70, 160, 250, and 300 kDa corresponding to monomers, dimers, tetramers, and oligomers of AChE, respectively crosslinked with the A beta peptide. Our results suggest that AChE and the A beta peptide may be involved in physiologically relevant interactions, related to the pathogenesis of Alzheimer disease (AD).
ESTHER : Opazo_1998_Mol.Chem.Neuropathol_33_39
PubMedSearch : Opazo_1998_Mol.Chem.Neuropathol_33_39
PubMedID: 9493175

Title : Kinetic and thermodynamic effects of acetylcholinesterase on the solubility of Abeta peptide -
Author(s) : Perez D , Alarcon R , Inestrosa NC
Ref : Journal de Physiologie (Paris) , 92 :479 , 1998
PubMedID:

Title : At least two receptors of asymmetric acetylcholinesterase are present at the synaptic basal lamina of Torpedo electric organ - Casanueva_1998_Biochem.Biophys.Res.Commun_250_312
Author(s) : Casanueva OI , Deprez P , Garcia-Huidobro T , Inestrosa NC
Ref : Biochemical & Biophysical Research Communications , 250 :312 , 1998
Abstract : Asymmetric acetylcholinesterase (AChE) is anchored to the basal lamina (BL) of cholinergic synapses via its collagenic tail, yet the complement of matrix receptors involved in its attachment remains unknown. The development of a novel overlay technique has allowed us to identify two Torpedo BL components that bind asymmetric AChE: a polypeptide of approximately 140 kDa and a doublet of 195-215 kDa. These were found to stain metachromatically with Coomassie blue R-250, were solubilized by acetic acid, and were sensitive to collagenase treatment. Upon sequence analysis, the 140 kDa polypeptide yielded a characteristic collagenous motif. Another AChE-binding BL constituent, identified by overlay, corresponded to a heparan sulfate proteoglycan. Lastly, we established that this proteoglycan, but not the collagenous proteins, interacted with at least one heparin binding domain of the collagenic tail of AChE. Our results indicate that at least two BL receptors are likely to exist for asymmetric AChE in Torpedo electric organ.
ESTHER : Casanueva_1998_Biochem.Biophys.Res.Commun_250_312
PubMedSearch : Casanueva_1998_Biochem.Biophys.Res.Commun_250_312
PubMedID: 9753626

Title : A major portion of synaptic basal lamina acetylcholinesterase is detached by high salt- and heparin-containing buffers from rat diaphragm muscle and torpedo electric organ - Casanueva_1998_J.Biol.Chem_273_4258
Author(s) : Casanueva OI , Garcia-Huidobro T , Campos EO , Aldunate R , Garrido J , Inestrosa NC
Ref : Journal of Biological Chemistry , 273 :4258 , 1998
Abstract : Collagen-tailed asymmetric acetylcholinesterase (AChE) forms are believed to be anchored to the synaptic basal lamina via electrostatic interactions involving proteoglycans. However, it was recently found that in avian and rat muscles, high ionic strength or polyanionic buffers could not detach AChE from cell-surface clusters and that these buffers solubilized intracellular non-junctional asymmetric AChE rather than synaptic forms of the enzyme. In the present study, asymmetric AChE forms were specifically solubilized by ionic buffers from synaptic basal lamina-enriched fractions, largely devoid of intracellular material, obtained from the electric organ of Torpedo californica and the end plate regions of rat diaphragm muscle. Furthermore, foci of AChE activity were seen to diminish in size, number, and staining intensity when the rat synaptic basal lamina-enriched preparations were treated with the extraction buffers. In the case of Torpedo, almost all the AChE activity was removed from the pure basal lamina sheets. We therefore conclude that a major portion of extracellular collagen-tailed AChE is extractable from rat and Torpedo synaptic basal lamina by high ionic strength and heparin buffers, although some non-extractable AChE activity remains associated with the junctional regions.
ESTHER : Casanueva_1998_J.Biol.Chem_273_4258
PubMedSearch : Casanueva_1998_J.Biol.Chem_273_4258
PubMedID: 9461624

Title : Brain acetylcholinesterase promotes amyloid-beta-peptide aggregation but does not hydrolyze amyloid precursor protein peptides - Campos_1998_Neurochem.Res_23_135
Author(s) : Campos EO , Alvarez A , Inestrosa NC
Ref : Neurochem Res , 23 :135 , 1998
Abstract : It has been suggested that acetylcholinesterase (AChE) has both a putative proteolytic activity against the amyloid precursor protein (APP), and a capacity to accelerate the assembly of amyloid-beta-peptide (Abeta) into Alzheimer's fibrils. Here, we have studied the ability of bovine brain AChE to share both activities. Results indicate that AChE purified through acridinium was able to process the APP peptides, however after further purification by an edrophonium column, the protease activity was lost. Under both conditions the capacity of the enzyme to promote amyloid formation was maintained. Kinetic studies of the Abeta aggregation process using edrophonium-AChE, indicated that the lag phase of the aggregation process was smaller than the one observed with the esterase purified by acridinium alone. Considering that the total amount of amyloid formed, measured by thioflavine-T fluorescence, was similar for both AChE preparations, our results suggest that the edrophonium-AChE possesses an higher intrinsic capacity to stimulate the aggregation of Abeta(1-40) peptide.
ESTHER : Campos_1998_Neurochem.Res_23_135
PubMedSearch : Campos_1998_Neurochem.Res_23_135
PubMedID: 9475506

Title : Molecular interactions of acetylcholinesterase with senile plaques - Inestrosa_1998_J.Physiol.Paris_92_341
Author(s) : Inestrosa NC , Alarcon R
Ref : Journal de Physiologie (Paris) , 92 :341 , 1998
Abstract : Acetylcholinesterase (AChE) present in Alzheimer plaques is resistant to low pH, anti-ChE inhibitors and high substrate concentrations in comparison with the free enzyme. Kinetic and pharmacological studies of AChE-amyloid complexes indicate that steric hindrance by the amyloid over the gorge and the peripheral site of AChE is responsible for these effects.
ESTHER : Inestrosa_1998_J.Physiol.Paris_92_341
PubMedSearch : Inestrosa_1998_J.Physiol.Paris_92_341
PubMedID: 9789834

Title : The Heparin-Binding Sites in the Collagenic Tail of Acetylcholinesterase - 1 -
Author(s) : Deprez P , Inestrosa NC
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :444 , 1998
PubMedID:

Title : The Heparin-Binding Sites in the Collagenic Tail of Acetylcholinesterase - 2 -
Author(s) : Deprez P , Krejci E , Inestrosa NC , Massoulie J
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :446 , 1998
PubMedID:

Title : Responses induced by tacrine in neuronal and non-neuronal cell lines - De Ferrari_1998_J.Neurosci.Res_52_435
Author(s) : De Ferrari GV , Von Bernhardi R , Calderon FH , Luza SC , Inestrosa NC
Ref : Journal of Neuroscience Research , 52 :435 , 1998
Abstract : Alzheimer's disease (AD) is associated with a reduction in cholinergic activity as a result of specific neuronal loss. Current potential treatments for the disease include both cholinomimetic drugs and anticholinesterase inhibitors. One of the drugs approved by the FDA is tacrine (9-amine-1,2,3,4 tetrahydroacridine; THA), a strong acetylcholinesterase (AChE) inhibitor. We have studied the effects of tacrine on glial and neuronal cells in culture assessing cell survival and viability and morphology. Lactate dehydrogenase (LDH) activity and methylthiazol-diphenyl-tetrazolium (MTT) reduction were used as toxicity indicators. We found that tacrine toxicity on rat B12 glial cells and mouse Neuro 2A cells was strongly dependent on its concentration (up to 500 microM) and time of exposure. The toxic effect was not prevented by serum factors nor by bovine serum albumin. Fluorescein-conjugated phalloidin was used to examine the arrangement of actin filaments at substrate adhesion regions and cell-cell contacts. Primary events following exposure to tacrine included changes in cell morphology, disappearance of actin filament bundles, and disruption of focal adhesion contacts. At concentrations between 10 and 50 microM, tacrine induced neurite outgrowth in Neuro 2A cells, an effect that was not observed in B12 cells, suggesting that certain tacrine effects could be specific for neuronal cells. Although similar trends of response were observed for both cell types, some differences between undifferentiated and differentiated cells were apparent.
ESTHER : De Ferrari_1998_J.Neurosci.Res_52_435
PubMedSearch : De Ferrari_1998_J.Neurosci.Res_52_435
PubMedID: 9589388

Title : Stable Complexes Involving Acetylcholinesterase and Amyloid-beta Peptide Change the Biochemical Properties of the Enzyme and Increase the Neurotoxicity of Alzheimer's Fibrils - Alvarez_1998_J.Neurosci_18_3213
Author(s) : Alvarez A , Alarcon R , Opazo C , Campos EO , Munoz FJ , Calderon FH , Dajas F , Gentry MK , Doctor BP , de Mello FG , Inestrosa NC
Ref : Journal of Neuroscience , 18 :3213 , 1998
Abstract : Brain acetylcholinesterase (AChE) forms stable complexes with amyloid-beta peptide (Abeta) during its assembly into filaments, in agreement with its colocalization with the Abeta deposits of Alzheimer's brain. The association of the enzyme with nascent Abeta aggregates occurs as early as after 30 min of incubation. Analysis of the catalytic activity of the AChE incorporated into these complexes shows an anomalous behavior reminiscent of the AChE associated with senile plaques, which includes a resistance to low pH, high substrate concentrations, and lower sensitivity to AChE inhibitors. Furthermore, the toxicity of the AChE-amyloid complexes is higher than that of the Abeta aggregates alone. Thus, in addition to its possible role as a heterogeneous nucleator during amyloid formation, AChE, by forming such stable complexes, may increase the neurotoxicity of Abeta fibrils and thus may determine the selective neuronal loss observed in Alzheimer's brain.
ESTHER : Alvarez_1998_J.Neurosci_18_3213
PubMedSearch : Alvarez_1998_J.Neurosci_18_3213
PubMedID: 9547230

Title : Dissection of the heparin-binding domains present in the collagenic tail of mammalian acetylcholinesterase -
Author(s) : Deprez P , Krejci E , Massoulie J , Inestrosa NC
Ref : Journal de Physiologie (Paris) , 92 :425 , 1998
PubMedID:

Title : Molecular Interactions of Acetylcholinesterase with the Synaptic Basal Lamina and the Senile Plaques -
Author(s) : Inestrosa NC , Alarcon R , Alvarez A , Calderon FH , Campos EO , Casanueva OI , De Ferrari GV , Deprez P , Garcia-Huidobro T , Munoz FJ , Perez D , Reyes AE
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :167 , 1998
PubMedID:

Title : Acetylcholinesterase Enhances the Neurotoxicity of beta-Amyloid Fibrils -
Author(s) : Munoz FJ , Inestrosa NC
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :182 , 1998
PubMedID:

Title : Identification of an Acetylcholinesterase Fragment that Promotes Alzheimer beta-Amyloid Fibril Formation -
Author(s) : De Ferrari GV , Inestrosa NC
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :185 , 1998
PubMedID:

Title : Differential Effect of Acetylcholinesterase on Neuronal and Glial Cells in Culture -
Author(s) : Calderon FH , Inestrosa NC
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :187 , 1998
PubMedID:

Title : Developmental regulation of mouse brain monomeric acetylcholinesterase - Moreno_1998_Int.J.Dev.Neurosci_16_123
Author(s) : Moreno RD , Campos FO , Dajas F , Inestrosa NC
Ref : Int J Developmental Neuroscience , 16 :123 , 1998
Abstract : Acetylcholinesterase (AChE) molecular forms were studied during mouse brain development. Mouse embryos expressed a monomeric (G1) and a tetrameric (G4) AChE form. Our results indicate that G4 AChE expressed at embryonic day (ED) 9 and ED15 could be purified by acridinium-Sepharose chromatography and shared similar biochemical and kinetic properties with the adult form. However, the G1 form expressed at either embryonic stage did not bind to acridinium, was not inhibited by excess substrate, and possessed higher K(m) and lower Vmax values than the adult G1 form. Two peripheral anionic binding site inhibitors, fasciculin and propidium, had a significantly lower affinity for the monomeric form at ED9. Results are discussed in terms of the biological significance of the embryonic G1 form, and its resemblance to the AChE activity found, associated with the senile plaques present in the brains of Alzheimer's patients.
ESTHER : Moreno_1998_Int.J.Dev.Neurosci_16_123
PubMedSearch : Moreno_1998_Int.J.Dev.Neurosci_16_123
PubMedID: 9762585

Title : Estrogen protects neuronal cells from the cytotoxicity induced by acetylcholinesterase-amyloid complexes - Bonnefont_1998_FEBS.Lett_441_220
Author(s) : Bonnefont AB , Munoz FJ , Inestrosa NC
Ref : FEBS Letters , 441 :220 , 1998
Abstract : The senile plaques present in Alzheimer's disease (AD) are composed of a core of amyloid beta-peptide (Abeta) plus several proteins including acetylcholinesterase (AChE). Recently we found that AChE forms complexes with the Abeta peptide in vitro and that these are more cytotoxic than Abeta fibrils alone. Considering that estrogen has been reported to act as a protective agent against Abeta-induced cytotoxicity, the effect of 17beta-estradiol was studied in rat pheochromocytoma (PC12) and mouse neuroblastoma (Neuro 2a) cells exposed to either Abeta alone or AChE-Abeta complexes. Estrogen showed a powerful protective effect in response to the challenge of AChE-Abeta complexes as well as with Abeta fibrils. This was also the case for other cytotoxic agents such as glutamate and H2O2. Our results suggest a common mechanism for cellular protection by estrogen against the toxicity of both Abeta fibrils and AChE-Abeta complexes, likely avoiding the free radical apoptotic pathway.
ESTHER : Bonnefont_1998_FEBS.Lett_441_220
PubMedSearch : Bonnefont_1998_FEBS.Lett_441_220
PubMedID: 9883888

Title : Laminin blocks the assembly of wild-type A beta and the Dutch variant peptide into Alzheimer's fibrils - Bronfman_1998_Amyloid_5_16
Author(s) : Bronfman FC , Alvarez A , Morgan C , Inestrosa NC
Ref : Amyloid , 5 :16 , 1998
Abstract : Amyloid fibril formation is believed to be a nucleation-dependent polymerization process which may be influenced by various other factors with important consequences for the development, prevention or treatment of amyloidosis. We have previously shown that laminin inhibits A beta peptide fibril formation in vitro. Here we present a kinetic study that indicates laminin to be a potent anti-amyloidosis factor, as it not only inhibited A beta 1-40 fibril aggregation, but also inhibited the aggregation of the Dutch A beta 1-40 variant, a peptide with a higher capacity to aggregate than the wild-type A beta 1-40. The inhibitory effect of laminin on amyloid fibril formation was not overcome by the addition of pre-formed A beta fibrils, suggesting that laminin inhibits the fibril elongation process. At the present time, however, we cannot rule out the possibility that laminin also affects the initial nucleation process of A beta fibril formation. On other hand, laminin was not able to counteract the amyloid fibril formation promoted by acetylcholinesterase (AChE), another component of the amyloid deposits found in AD brains. The effect of laminin may be important as an inhibitor of A beta amyloidogenesis in vivo, specifically at the level of cerebral blood vessels.
ESTHER : Bronfman_1998_Amyloid_5_16
PubMedSearch : Bronfman_1998_Amyloid_5_16
PubMedID: 9547001

Title : Toxic effects of acetylcholinesterase on neuronal and glial-like cells in vitro - Calderon_1998_Mol.Psychiatry_3_247
Author(s) : Calderon FH , Von Bernhardi R , De Ferrari GV , Luza S , Aldunate R , Inestrosa NC
Ref : Mol Psychiatry , 3 :247 , 1998
Abstract : Acetylcholinesterase (AChE), the enzyme involved in the hydrolysis of the neurotransmitter acetylcholine, has been implicated in non-cholinergic actions which may play a role in neurodegenerative diseases such as Alzheimer's disease. To study the potential cytotoxicity of brain AChE, the effects of affinity purified AChE were analyzed on neuronal (Neuro 2a) and glial-like (B12) cells. LDH release and MTT reduction assays showed that AChE was toxic; the toxicity was dependent on the enzyme concentration, time of incubation and cellular density. The toxic effect of AChE was not related to its catalytic activity, since the anti-cholinesterase drug BW284C51 and heat inactivation were unable to block the effects of the enzyme. When cells were incubated at 4 degrees C, toxicity was completely blocked, in contrast to cells incubated at 37 degrees C. The presence of serum in the culture medium inhibited the toxic effects of AChE. Cytoplasmic shrinkage, condensation and fragmentation of nucleus as well as DNA strand breaks detected with the TUNEL technique indicated that apoptotic cell death is involved in the effect of AChE. Considering that we have previously shown that AChE promotes the assembly of beta-amyloid peptide into neurotoxic amyloid fibrils, it is conceivable that the neurotoxicity of AChE shown here may play a role in the neuronal degeneration observed in Alzheimer's disease.
ESTHER : Calderon_1998_Mol.Psychiatry_3_247
PubMedSearch : Calderon_1998_Mol.Psychiatry_3_247
PubMedID: 9672900

Title : A monoclonal antibody against acetylcholinesterase inhibits the formation of amyloid fibrils induced by the enzyme - Reyes_1997_Biochem.Biophys.Res.Commun_232_652
Author(s) : Reyes AE , Perez DR , Alvarez A , Garrido J , Gentry MK , Doctor BP , Inestrosa NC
Ref : Biochemical & Biophysical Research Communications , 232 :652 , 1997
Abstract : A monoclonal antibody (mAb) 25B1 directed against fetal bovine-serum acetylcholinesterase (FBS AChE) was used to examine the ability of the cholinergic enzyme to promote the assembly of amyloid-beta peptides (A beta) into Alzheimer fibrils. This mAb binds to the peripheral anionic site of the enzyme and allosterically inhibits catalytic activity of FBS AChE. Several techniques, including thioflavine-T fluorescence, turbidity, and negative-staining at the electron microscopy level, were used to assess amyloid formation. Inhibition of amyloid formation was dependent on the molar ratio AChE:mAb 25B1, and at least 50% of the inhibition of the AChE promoting effect occurs at a molar ratio similar to that required for inhibition of the esterase activity. Our results suggest that mAb 25B1 inhibits the promotion of the amyloid fibril formation triggered by AChE by affecting the lag period of the A beta aggregation process.
ESTHER : Reyes_1997_Biochem.Biophys.Res.Commun_232_652
PubMedSearch : Reyes_1997_Biochem.Biophys.Res.Commun_232_652
PubMedID: 9126330

Title : Acetylcholinesterase promotes the aggregation of amyloid-beta-peptide fragments by forming a complex with the growing fibrils - Alvarez_1997_J.Mol.Biol_272_348
Author(s) : Alvarez A , Opazo C , Alarcon R , Garrido J , Inestrosa NC
Ref : Journal of Molecular Biology , 272 :348 , 1997
Abstract : Acetylcholinesterase (AChE), an enzyme involved in the hydrolysis of the neurotransmitter acetylcholine, consistently colocalizes with the amyloid deposits characteristic of Alzheimer's disease and may contribute to the generation of amyloid proteins and/or physically affect fibril assembly. In order to identify the structural domains of the amyloid-beta-peptide (Abeta) involved in the aggregation induced by AChE, we have studied the effect of this cholinergic enzyme on Abeta peptide fragments of different sizes. AChE enhanced the aggregation of the Abeta(12-28) and Abeta(25-35) peptides but not of the Abeta(1-16) fragment. The inductive effect of AChE on the aggregation of Abeta(12-28) was abolished by the presence of either Abeta(1-16) or Abeta(9-21). The effect of the enzyme was also analysed using two different mutant fragments, possessing a low and the other a high capacity for fibrillogenesis. The fragments used were Abeta(12-28)Val18-->Ala and Abeta(12-28)Glu22-->Gln, respectively. AChE was able to promote the aggregation of these fragments in a very specific way and both mutant peptides were able to form amyloid fibrils, as revealed by negative staining under the electron microscope. Binding assays indicated that AChE was bound to Abeta(12-28), as well as to the Abeta(1-16) peptide. AChE was seen to form strong complexes with the Abeta(12-28) fibrils as such complexes stained positively for both thioflavine-T and AChE activity, were resistant to high ionic strength treatment, and were partially sensitive to detergents, suggesting that hydrophobic interactions may play a role in the stabilization of the AChE-Abeta complex. Our results suggest that such amyloid-AChE complexes are formed when AChE interacts with the growing amyloid fibrils and accelerates the assembly of Abeta peptides. This is consistent with the fact that AChE is known to be present within Abeta deposits including the pre-amyloid diffuse and mature senile plaques found in Alzheimer's brain.
ESTHER : Alvarez_1997_J.Mol.Biol_272_348
PubMedSearch : Alvarez_1997_J.Mol.Biol_272_348
PubMedID: 9325095

Title : Tetrameric (G4) acetylcholinesterase: structure, localization, and physiological regulation. - Fernandez_1996_J.Neurochem_66_1335
Author(s) : Fernandez HL , Moreno RD , Inestrosa NC
Ref : Journal of Neurochemistry , 66 :1335 , 1996
Abstract : Acetylcholinesterase (AChE), a highly conserved enzyme in the animal kingdom, is distributed throughout a wide range of vertebrate tissues where it is expressed as multiple molecular forms comprising different arrangements of catalytic and structural subunits. The major AChE form in the CNS is an amphiphilic globular tetramer (G4 AChE) consisting of four identical catalytic subunits attached to cellular membranes by a hydrophobic noncatalytic subunit (P-subunit). This study focuses primarily on current data involving the structure of the G4 AChE P-subunit, the expression and regulation of G4 AChE during development and adulthood, and its role(s) in certain neurological disorders including Alzheimer's disease.
ESTHER : Fernandez_1996_J.Neurochem_66_1335
PubMedSearch : Fernandez_1996_J.Neurochem_66_1335
PubMedID: 8627284

Title : Amyloid precursor protein fragment and acetylcholinesterase increase with cell confluence and differentiation in a neuronal cell line - Bronfman_1996_Exp.Cell.Res_229_93
Author(s) : Bronfman FC , Fernandez HL , Inestrosa NC
Ref : Experimental Cell Research , 229 :93 , 1996
Abstract : This study addresses the developmental regulation of amyloid precursor protein (APP) fragments comprising the amyloid-beta peptide (AP) and the amyloid-promoting factor acetylcholinesterase (AChE) in a mouse neuronal cell line (Neuro-2a). Results indicate that a 35-kDa amyloidogenic fragment of APP and the major molecular forms of AChE (G1 and G4) in Neuro-2a cells significantly increase with increasing levels of cell confluence. The foregoing molecules undergo further increases when neuroblastoma cells differentiate in the presence of dibutyryl cAMP. In contrast, a 17-kDa fragment of APP and butyrylcholinesterase were not affected by cell confluence or differentiation. These findings are the first to indicate that a selective Abeta-containing fragment of APP is subject to developmental regulation. Moreover, our data show that the 35-kDa fragment and AChE forms respond in parallel to the same developmental stimuli, i.e., cell confluence and differentiation. This points to the existence of a functional relationship between both molecules, a notion that is consistent with the potential role that has been ascribed to AChE in both APP processing and the formation of amyloid deposits in Alzheimer's brains.
ESTHER : Bronfman_1996_Exp.Cell.Res_229_93
PubMedSearch : Bronfman_1996_Exp.Cell.Res_229_93
PubMedID: 8940253

Title : Acetylcholinesterase accelerates assembly of amyloid-beta-peptides into Alzheimer's fibrils: possible role of the peripheral site of the enzyme - Inestrosa_1996_Neuron_16_881
Author(s) : Inestrosa NC , Alvarez A , Perez CA , Moreno RD , Vicente M , Linker C , Casanueva OI , Soto C , Garrido J
Ref : Neuron , 16 :881 , 1996
Abstract : Acetylcholinesterase (AChE), an important component of cholinergic synapses, colocalizes with amyloid-beta peptide (A beta) deposits of Alzheimer's brain. We report here that bovine brain AChE, as well as the human and mouse recombinant enzyme, accelerates amyloid formation from wild-type A beta and a mutant A beta peptide, which alone produces few amyloid-like fibrils. The action of AChE was independent of the subunit array of the enzyme, was not affected by edrophonium, an active site inhibitor, but it was affected by propidium, a peripheral anionic binding site ligand. Butyrylcholinesterase, an enzyme that lacks the peripheral site, did not affect amyloid formation. Furthermore, AChE is a potent amyloid-promoting factor when compared with other A beta-associated proteins. Thus, in addition to its role in cholinergic synapses, AChE may function by accelerating A beta formation and could play a role during amyloid deposition in Alzheimer's brain.
ESTHER : Inestrosa_1996_Neuron_16_881
PubMedSearch : Inestrosa_1996_Neuron_16_881
PubMedID: 8608006

Title : Acetylcholinesterase, a senile plaque component, affects the fibrillogenesis of amyloid-beta-peptides - Alvarez_1995_Neurosci.Lett_201_49
Author(s) : Alvarez A , Bronfman F , Perez CA , Vicente M , Garrido J , Inestrosa NC
Ref : Neuroscience Letters , 201 :49 , 1995
Abstract : Acetylcholinesterase (AChE) colocalizes with amyloid-beta peptide (A beta) deposits present in the brain of Alzheimer's patients. Recent studies showed that A beta 1-40 can adopt two different conformational states in solution (an amyloidogenic conformer, A beta ac, and a non-amyloidogenic conformer, A beta nac) which have distinct abilities to form amyloid fibrils. We report here that AChE binds A beta nac and accelerates amyloid formation by the same peptide. No such effect was observed with A beta ac, the amyloidogenic conformer, suggesting that AChE acts as a 'pathological chaperone' inducing a conformational transition from A beta nac into A beta ac in vitro.
ESTHER : Alvarez_1995_Neurosci.Lett_201_49
PubMedSearch : Alvarez_1995_Neurosci.Lett_201_49
PubMedID: 96274631

Title : Effect of protamine on the solubilization of collagen-tailed acetylcholinesterase: potential heparin-binding consensus sequences in the tail of the enzyme - Deprez_1995_Biochim.Biophys.Acta_1252_53
Author(s) : Deprez PN , Signorelli J , Inestrosa NC
Ref : Biochimica & Biophysica Acta , 1252 :53 , 1995
Abstract : Asymmetric acetylcholinesterase (AChE) contains three tetrameric sets of catalytic subunits disulfide-linked to structural subunits of a collagenic tail. This form is localized in the basement membrane zone of the neuromuscular junction, where it interacts with proteoglycans. It has been described that heparin-binding domains of many proteins contains clusters of basic residues. Here we show that protamine--a highly basic protein--specifically solubilizes asymmetric AChE from the rat neuromuscular junction, starting at 25 micrograms/ml and reaching a plateau at 250 micrograms/ml protamine. We also show that protamine was able to displace AChE bound to heparin-agarose. Two synthetic peptides corresponding to the sequence of the collagenic tail polypeptide also release the enzyme. Finally, we propose that two heparin-binding consensus sequences (-B-B-X-B-) are present in the tail of AChE. Our results indicate that clusters of basic residues are responsible for the interaction of the collagen-tailed AChE with proteoglycans.
ESTHER : Deprez_1995_Biochim.Biophys.Acta_1252_53
PubMedSearch : Deprez_1995_Biochim.Biophys.Acta_1252_53
PubMedID: 7548166

Title : Two heparin-binding domains are present on the collagenic tail of asymmetric acetylcholinesterase - Deprez_1995_J.Biol.Chem_270_11043
Author(s) : Deprez P , Inestrosa NC
Ref : Journal of Biological Chemistry , 270 :11043 , 1995
Abstract : The collagen-tailed form of acetylcholinesterase (AChE) binds to heparin and heparan sulfate proteoglycans. We have employed synthetic peptides corresponding to the central collagenic region of the tail of AChE, to identify the heparin-binding domains of the tail of asymmetric AChE. Two putative heparin-binding consensus sequences were localized in the collagenic tail. Peptides containing such sequences (P-(145-159) and P-(249-262)) were able to release asymmetric AChE bound to heparin-agarose. A triple mutation, Asn-Asp-Gly-Gly instead of Arg-His-Gly-Arg, completely abolishes the capacity of the peptide P-(145-159) to elute AChE from the heparin column. Our results suggest that the interaction between the collagen-tailed AChE and proteoglycans is mediated by clusters of basic residues that form two belts around the triple helix of the collagenic tail.
ESTHER : Deprez_1995_J.Biol.Chem_270_11043
PubMedSearch : Deprez_1995_J.Biol.Chem_270_11043
PubMedID: 7744733

Title : Blood markers in Alzheimer disease: subnormal acetylcholinesterase and butyrylcholinesterase in lymphocytes and erythrocytes - Inestrosa_1994_J.Neurol.Sci_122_1
Author(s) : Inestrosa NC , Alarcon R , Arriagada J , Donoso A , Alvarez J , Campos EO
Ref : Journal of the Neurological Sciences , 122 :1 , 1994
Abstract : In patients with the clinical diagnosis of Alzheimer disease (AD), we searched for systemic changes in components of the blood as a diagnostic tool. The acetylcholine-related enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BCHE) were measured in plasma, erythrocytes, platelets and lymphocytes. Results did not show a general effect; notwithstanding, specific cell types presented alterations either in AChE or BCHE but not in both enzymatic activities. In AD patients, AChE of lymphocytes was reduced by 60% compared with the age-matched controls. However, when patients were divided, the sporadic but not the familial subgroup exhibited a significant reduction. In erythrocytes the BCHE activity was reduced by 45% in sporadic AD. The molecular forms of the lymphocyte AChE were characterized by velocity sedimentation. Both globular forms were subnormal, more so the tetrameric G4 AChE form than the G2 form.
ESTHER : Inestrosa_1994_J.Neurol.Sci_122_1
PubMedSearch : Inestrosa_1994_J.Neurol.Sci_122_1
PubMedID: 8195795

Title : Monomeric amphiphilic forms of acetylcholinesterase appear early during brain development and may correspond to biosynthetic precursors of the amphiphilic G4 forms - Inestrosa_1994_Neurosci.Lett_173_155
Author(s) : Inestrosa NC , Moreno RD , Fuentes ME
Ref : Neuroscience Letters , 173 :155 , 1994
Abstract : We have studied the development of mouse brain acetylcholinesterase (AChE). Only tetrameric (G4) and monomeric (G1) forms were detected both in vivo and in vitro. The amphiphilic G4 form increased continuously during development, whereas an amphiphilic G1 form appears transiently around embryonic day 17. A causal relationship between the monomers and tetramers was established using pulse-chase experiments with paraoxon, a reversible AChE inhibitor. We report here, for the first time, the presence of an amphiphilic monomer possibly involved in the assembly of the amphiphilic G4 AChE form during mouse brain development.
ESTHER : Inestrosa_1994_Neurosci.Lett_173_155
PubMedSearch : Inestrosa_1994_Neurosci.Lett_173_155
PubMedID: 7936404

Title : Sensitivity of acetylcholinesterase molecular forms to inhibition by high MgCl2 concentration - Inestrosa_1994_Biochim.Biophys.Acta_1208_286
Author(s) : Inestrosa NC , Perez CA , Simpfendorfer RW
Ref : Biochimica & Biophysica Acta , 1208 :286 , 1994
Abstract : Previous studies have shown that the asymmetric (A12) and the dimeric (G2), but not the tetrameric (G4), acetylcholinesterase (AChE) forms are inactivated by high MgCl2 concentration (Perelman and Inestrosa (1989) Anal. Biochem. 180, 227-230). Here we show that the effect of MgCl2 on AChE activity corresponds to an irreversible inhibition and is not due to environmental effects related to the different extraction media. The anchor domain in each AChE form was not involved in the differential MgCl2 sensitivity. Monomers derived from the various AChE forms behave in a way similar to that of the original assembled forms. Purified AChE molecular forms showed the same sensitivity to MgCl2, than the same enzyme forms studied in tissue extracts. Neither the affinity for the substrate nor the inhibition by excess substrate of the residual AChE activity were affected by high MgCl2 concentration. Results indicate that the differences between the tetrameric enzyme and the other two AChE molecular forms occur at the level of the catalytic subunit, probably due to differential post-translational processing.
ESTHER : Inestrosa_1994_Biochim.Biophys.Acta_1208_286
PubMedSearch : Inestrosa_1994_Biochim.Biophys.Acta_1208_286
PubMedID: 7947960

Title : Acetylcholinesterase changes in hearts with sinus rhythm and atrial fibrillation - Gonzalez_1993_Gen.Pharmacol_24_111
Author(s) : Gonzalez RA , Campos EO , Karmelic C , Moran S , Inestrosa NC
Ref : General Pharmacology , 24 :111 , 1993
Abstract : 1. Clinical and experimental evidence suggest that changes in the autonomic tone play a role in the pathogenesis of atrial fibrillation. 2. We have studied the distribution of molecular forms of acetylcholinesterase (AChE) in atrial biopsies obtained from individuals without arrhythmias and in patients with atrial fibrillation. 3. Analysis of the distribution of globular and asymmetric AChE forms, showed a decrease in the amount of the globular forms of biopsies taken from atria during fibrillation. 4. This study is the first attempt to characterize the molecular forms of AChE in the human heart of patients with sinus rhythm and chronic atrial fibrillation.
ESTHER : Gonzalez_1993_Gen.Pharmacol_24_111
PubMedSearch : Gonzalez_1993_Gen.Pharmacol_24_111
PubMedID: 8482484

Title : Amphiphilic behavior of a brain tetrameric acetylcholinesterase form lacking the plasma membrane anchoring domain - Fuentes_1992_Brain.Res_580_1
Author(s) : Fuentes ME , Inestrosa NC
Ref : Brain Research , 580 :1 , 1992
Abstract : We have studied the behavior of a mammalian brain tetrameric acetylcholinesterase (AChE) form released by proteinase K from a crude membrane fraction of bovine caudate nucleus. The solubilization of active AChE indicated the presence of a protease-sensitive site in the anchored protein. Unexpectedly, the solubilized AChE maintained its capacity to form aggregates in detergent-free gradients. We demonstrate here that this property was due neither to the presence of the hydrophobic membrane-anchoring domain still linked to the enzyme, nor to the presence of AChE activity trapped in small plasma membrane vesicles. Moreover, we found that the proteinase K-treated extract, devoid of AChE activity, induced the aggregation of purified hydrophilic AChE which usually does not form aggregates. Our results suggest the presence of an AChE aggregating factor in bovine brain extracts prepared in the presence of proteinase K. It is possible that this aggregation may reflect a process of AChE clustering on neurons.
ESTHER : Fuentes_1992_Brain.Res_580_1
PubMedSearch : Fuentes_1992_Brain.Res_580_1
PubMedID: 1504788

Title : Binding of Asymmetric (Al2) Acetylcholinesterase to C2 Muscle Cells and to Cho Mutants Defective in Glycosaminoglycan Synthesis -
Author(s) : Inestrosa NC , Gordon H
Ref : In Multidisciplinary approaches to cholinesterase functions - Proceedings of Fourth International Meeting on Cholinesterases , (Shafferman, A. and Velan, B., Eds) Plenum Press, New York :25 , 1992
PubMedID:

Title : Characterization of acetylcholinesterase from human heart auricles: evidence for the presence of a G-form sensitive to phosphatidylinositol-specific phospholipase c - Gonzalez_1991_Gen.Pharmacol_22_107
Author(s) : Gonzalez R , Campos EO , Moran S , Inestrosa NC
Ref : General Pharmacology , 22 :107 , 1991
Abstract : 1. Acetylcholinesterase (AChE) is an important enzyme of the cholinergic system in mammals. 2. We report here the subcellular association of the AChE molecular forms in the normal human heart auricle. 3. Both globular (G) and asymmetric (A) forms were identified using velocity sedimentation and sequential extraction procedures. 4. G forms corresponds to 84% and A forms account for 16% of the total AChE activity. 5. Of G forms 64% of AChE activity correspond to the G1 monomer and of the A forms the class I-A account for 80% of AChE activity. 6. In addition, treatment of the cardiac membranes with the enzyme phosphatidylinositol-specific phospholipase c (PIPLC) results in the solubilization of AChE activity. 7. This means that a G2 AChE dimer with a glycolipid anchoring domain is present in the human heart.
ESTHER : Gonzalez_1991_Gen.Pharmacol_22_107
PubMedSearch : Gonzalez_1991_Gen.Pharmacol_22_107
PubMedID: 1646743

Title : A comparison of the Xenopus laevis oocyte acetylcholinesterase with the muscle and brain enzyme suggests variations at the post-translational level - Moya_1991_Comp.Biochem.Physiol.C_98_299
Author(s) : Moya MA , Fuentes ME , Inestrosa NC
Ref : Comparative Biochemistry & Physiology C Pharmacol Toxicol , 98 :299 , 1991
Abstract : 1. Xenopus laevis oocytes express endogenously two components of the cholinergic system: the muscarinic receptors and the acetylcholinesterase (AChE). 2. A biochemical characterization of this enzyme was carried out. 3. The results established that the activity found in the oocytes correspond to 'true' AChE with a molecular weight of 65,000 Da and a sedimentation coefficient of 3-4 S. 4. The enzyme aggregates in the absence of detergent suggesting that it possess an hydrophobic character; despite that, it is not sensitive to PIPLC. 5. A comparison with the Xenopus brain and muscle AChE shows different post-translational modifications and catalytic properties with the oocyte AChE.
ESTHER : Moya_1991_Comp.Biochem.Physiol.C_98_299
PubMedSearch : Moya_1991_Comp.Biochem.Physiol.C_98_299
PubMedID: 1676945

Title : Differential association and distribution of acetyl- and butyrylcholinesterases within rat liver subcellular organelles - Perelman_1990_J.Biol.Chem_265_214
Author(s) : Perelman A , Abeijon C , Hirschberg CB , Inestrosa NC , Brandan E
Ref : Journal of Biological Chemistry , 265 :214 , 1990
Abstract : Rat liver cholinesterases were found to share properties and characteristics with those expressed in cholinergic tissues. The distribution and presence of different molecular forms of cholinesterases in different subcellular organelles of rat liver were studied. The rough and smooth endoplasmic reticulum and Golgi apparatus were enriched in the G4 molecular form of acetylcholinesterase (AChE) (relative to the G2 molecular form), while the inverse was found in the plasma membrane. The interaction of these molecular forms of AChE with the Golgi membrane was studied in detail. Approximately one-half of the G4 form was free within the lumen while the remainder was an intrinsic membrane protein; all the G2 molecular form was anchored to the membrane via phosphatidylinositol. Only the G1 and G2 molecular forms of butyrylcholinesterase (BCHE) were found in the above subcellular organelles; both molecular forms were soluble within the lumen of Golgi vesicles. These results indicate that rat liver expresses several molecular forms of AChE which have multiple interactions with membranes and that liver is unlikely to be the source of the G4 form of BCHE present in high concentration in the plasma.
ESTHER : Perelman_1990_J.Biol.Chem_265_214
PubMedSearch : Perelman_1990_J.Biol.Chem_265_214
PubMedID: 2152920

Title : [Biotechnological aspects in loco larvae]. [Spanish] - Inestrosa_1990_Arch.Biol.Med.Exp_23_179
Author(s) : Inestrosa NC , Labarca R , Perelman A , Campos EO , Araneda R , Gonzalez M , Brandan E , Sanchez JP , Gonzalez-Plaza R
Ref : Archivos de Biologia y Medicina Experimentales , 23 :179 , 1990
Abstract : The biology of planktotrophic larvae of Concholepas concholepas is the main bottleneck towards developing biotechnologies to rear this muricid. Data concerning planktonic larvae development, diets and environmental signals triggering larval settlement and recruitment is scarce. We have begun the study of the molecular and cell biology of embryos, larvae and recruits having as a final goal, the development of appropriate biotechnologies to rear this gastropod. First, an inverse ratio between BCHE and AChE enzyme activities was established. This ratio may be a precise developmental marker for this species. Second, for the first time a phosphoinositide related regulatory pathway is reported in a muricid, opening a new approach to the biotechnological management of larvae. Third, the relation between sulfate in sea water and larval motility was studied. Concentrations below 125 microM sulfate decreases larval motility. The sulfate is incorporated in proteoglycans which participate in different developmental phenomena. Lastly, a genomic Concholepas concholepas DNA sequence, similar to that of a human growth hormone probe was detected. This is very interesting since growth factors are key molecules during development, growth and are involved in food conversion rates in fish and also, in a variety of marine invertebrates.
ESTHER : Inestrosa_1990_Arch.Biol.Med.Exp_23_179
PubMedSearch : Inestrosa_1990_Arch.Biol.Med.Exp_23_179
PubMedID: 1966831

Title : Motor nerve regulates muscle extracellular matrix proteoglycan expression - Fadic_1990_J.Neurosci_10_3516
Author(s) : Fadic R , Brandan E , Inestrosa NC
Ref : Journal of Neuroscience , 10 :3516 , 1990
Abstract : Denervation of rat leg muscles caused a 2-3-fold increase in 35S-sulfate and 3H-glucosamine incorporation into proteoglycans of the muscle extracellular matrix. The size of the proteoglycans and the glycosaminoglycan chain length and degree of sulfation were unchanged. Because the rate of degradation of proteoglycans was also unchanged by denervation, we infer that denervation increases proteoglycan synthesis. Muscle reinnervation restored the original rate of synthesis of proteoglycans. Paralysis of innervated muscle caused increased incorporation of sulfate comparable to that seen in denervation. Thus motor nerve activity appears to regulate the level of proteoglycans in the muscle extracellular matrix.
ESTHER : Fadic_1990_J.Neurosci_10_3516
PubMedSearch : Fadic_1990_J.Neurosci_10_3516
PubMedID: 2230941

Title : Dermatan sulfate and de-sulfated heparin solubilized collagen-tailed acetylcholinesterase from the rat neuromuscular junction - von Bernhardi_1990_Brain.Res_529_91
Author(s) : Von Bernhardi R , Inestrosa NC
Ref : Brain Research , 529 :91 , 1990
Abstract : We are interested in the study of the interactions involved in the attachment of collagen-tailed acetylcholinesterase (AChE) to the synaptic basal lamina. The fact that AChE occupies less than 0.1% of the muscle basal lamina, suggests that there is a very high specificity in the interaction that defines its distribution. We have previously found that asymmetric AChE is bound to the neuromuscular junction via heparan sulfate proteoglycans. Sulfated glycosaminoglycans as heparan sulfate and heparin extracted the asymmetric AChE from the synaptic basal lamina. Here we show that dermatan sulfate as well as de-sulfated heparin, are also able to extract collagen-tailed AChE. Taking into account that the solubilization of the asymmetric AChE is concomitant with the liberation of a dermatan sulfate proteoglycan from the rat neuromuscular junction, the present results open the possibility that the collagen-tailed AChE is also anchored to dermatan sulfate proteoglycans at the synaptic basal lamina.
ESTHER : von Bernhardi_1990_Brain.Res_529_91
PubMedSearch : von Bernhardi_1990_Brain.Res_529_91
PubMedID: 2282507

Title : Carrageenans solubilize asymmetric acetylcholinesterase from nicotinic cholinergic synapses - von Bernhardi_1990_Comp.Biochem.Physiol.C_96_77
Author(s) : Von Bernhardi R , Ayal H , Inestrosa NC
Ref : Comparative Biochemistry & Physiology C Pharmacol Toxicol , 96 :77 , 1990
Abstract : 1. Acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylcholine at cholinergic synapses in both vertebrate and invertebrates organisms. 2. The asymmetric synaptic AChE is attached to the extracellular matrix (ECM) of the neuromuscular junction through heparin sulphate proteoglycans (HSPGs). 3. It has been shown previously that heparin-like glycosaminoglycans (GAGs) can solubilize this enzyme from the cholinergic synapses. 4. The present paper describes the solubilization of asymmetric AChE by different marine macroalgal polysaccharides, called carrageenans. 5. Important differences were found among all the carrageenans tested; they released 15-50% of the total AChE activity normally solubilized by heparin. 6. Carrageenans extracted from tetrasporic stages of Iridaea ciliata and I. membranacea were always better extracting agents than those from the cystocarpic stages of these algae, suggesting that lambda-like carrageenans are involved. 7. This hypothesis was confirmed by extracting AChE with purified carrageenans.
ESTHER : von Bernhardi_1990_Comp.Biochem.Physiol.C_96_77
PubMedSearch : von Bernhardi_1990_Comp.Biochem.Physiol.C_96_77
PubMedID: 1980885

Title : Association of acetylcholinesterase with the cell surface. -
Author(s) : Inestrosa NC , Perelman A
Ref : Journal of Membrane Biology , 118 :1 , 1990
PubMedID: 2283677

Title : A simple assay to estimate the acetylcholinesterase molecular forms in crude extracts of rat skeletal muscle - Perelman_1989_Anal.Biochem_180_227
Author(s) : Perelman A , Inestrosa NC
Ref : Analytical Biochemistry , 180 :227 , 1989
Abstract : All the current methods available for analyzing the acetylcholinesterase (AChE) molecular forms are time consuming and require the use of expensive equipment. We have found that by using the differential inactivation of globular (G4 + G1) and asymmetric AChE forms by high Mg2+ concentration, we can set up a very easy and quick assay that allows us to determine the relative proportions of AChE molecular forms present in rat skeletal muscles. This assay will be of great help in estimating changes in the muscle AChE forms under experimental conditions that require several simultaneous determinations.
ESTHER : Perelman_1989_Anal.Biochem_180_227
PubMedSearch : Perelman_1989_Anal.Biochem_180_227
PubMedID: 2817352

Title : Phosphatidylinositol-specific phospholipase C solubilized G2 acetylcholinesterase from plasma membranes of chromaffin cells - Prieto_1989_J.Neurosci.Res_24_169
Author(s) : Prieto AL , Fuentes ME , Arqueros L , Inestrosa NC
Ref : Journal of Neuroscience Research , 24 :169 , 1989
Abstract : Using whole homogenates and defined subcellular fractions of bovine adrenal medulla, we investigated the properties of the dimeric G2 molecular form of acetylcholinesterase (AChE), its distribution, and the mode of attachment to chromaffin cells. Our studies indicate that a substantial fraction of the G2 form is specifically susceptible to solubilization by phosphatidylinositol-specific phospholipase C (PIPLC) from subcellular fractions enriched with plasma membrane fragments. The results suggest that the G2 form of AChE is anchored in the plasma membrane to a glycolipid domain that contains phosphatidylinositol. Since a Ca+2-dependent PIPLC has been previously described in chromaffin granules, it is possible that the adrenal AChE could be released by a system reminiscent of that involved in the case of the surface glycoprotein of Trypanosoma brucei.
ESTHER : Prieto_1989_J.Neurosci.Res_24_169
PubMedSearch : Prieto_1989_J.Neurosci.Res_24_169
PubMedID: 2585545

Title : Distribution and anchoring of molecular forms of acetylcholinesterase. - Inestrosa_1989_TIPS_10_325
Author(s) : Inestrosa NC , Perelman A
Ref : Trends in Pharmacological Sciences , 10 :325 , 1989
Abstract : Molecular forms of acetylcholinesterase exhibit tissue-specific distribution, and each form is anchored to the cell surface via a particular post-translational modification of the catalytic subunit. Nibaldo Inestrosa and Alejandra Perelman review evidence that heparan sulphate proteoglycans are the extracellular matrix receptors for the collagen-tailed enzyme, and that a glycolipid which contains phosphatidylinositol and a 20 kDa hydrophobic peptide participate in the anchoring of the hydrophobic globular forms of acetylcholinesterase to the cell surface.
ESTHER : Inestrosa_1989_TIPS_10_325
PubMedSearch : Inestrosa_1989_TIPS_10_325
PubMedID: 2686130

Title : Nerve regulation of class I and class II-asymmetric forms of acetylcholinesterase in rat skeletal muscles - Fadic_1989_J.Neurosci.Res_22_449
Author(s) : Fadic R , Inestrosa NC
Ref : Journal of Neuroscience Research , 22 :449 , 1989
Abstract : Two classes of collagen-tailed, asymmetric forms (A-forms) of acetylcholinesterase (AChE) have been described in skeletal muscles of vertebrates. They are distinguished by their different solubilization requirements: class I A-forms are solubilized in the presence of high salt, whereas class II A-forms require in addition a chelating agent for solubilization. We report here that class II A-forms are less sensitive to nerve section than are class I A-forms. The latter form decreases faster and to a lower level of activity after denervation. The decay of both AChE classes is more rapidly in short-stump nerves than in long ones. The effect of nerve section on class II A-forms appears to be dependent on the particular muscle group being studied. Both classes of A-forms reappear after muscle reinnervation, but the class I A-forms recovered earlier. More interestingly, both classes of A-forms increase in normally innervated skeletal muscles after contralateral nerve injury. In this case, however, the class II A-forms change first. Muscular disuse induced by contralateral tenotomy is also followed by a rise in class II A-forms. Our results, showing differences in response and flexibility in the changes of the two classes of A-forms in several experimental conditions, represent a relevant contribution to the understanding of the regulation and functional role of the asymmetric forms of AChE in vertebrate skeletal muscles.
ESTHER : Fadic_1989_J.Neurosci.Res_22_449
PubMedSearch : Fadic_1989_J.Neurosci.Res_22_449
PubMedID: 2760943

Title : Characterization of a tetrameric G4 form of acetylcholinesterase from bovine brain: a comparison with the dimeric G2 form of the electric organ - Fuentes_1988_Mol.Cell.Biochem_81_53
Author(s) : Fuentes ME , Inestrosa NC
Ref : Molecular & Cellular Biochemistry , 81 :53 , 1988
Abstract : Globular forms (G forms) of acetylcholinesterase (AChE) are formed by monomers, dimers and tetramers of the catalytic subunits (G1, G2 and G4). In this work the hydrophobic G2 and G4 AChE forms were purified to homogeneity from Discopyge electric organ and bovine caudate nucleus and studied from different points of view, including: velocity sedimentation, affinity to lectins and SDS-polyacrylamide gel electrophoresis under reducing and non-reducing conditions. The polypeptide composition of Discopyge electric organ G2 is similar to Torpedo, however the pattern of the brain G4 AChE is much complex. Under non-reducing conditions the catalytic subunit possesses a molecular weight of 65 kDa, however this value increases to 68 kDa after reduction, suggesting that intrachain-disulfide bonds are important in the folding of the catalytic subunits of the AChE. Also it was found that after mild proteolysis; the (125I)-TID-20 kDa fragment decreased its molecular weight to approximately 10 kDa with little loss of AChE activity. Finally, we suggest a model for the organization of the different domains of the hydrophobic anchor fragment of the G4 form.
ESTHER : Fuentes_1988_Mol.Cell.Biochem_81_53
PubMedSearch : Fuentes_1988_Mol.Cell.Biochem_81_53
PubMedID: 3173345

Title : A 13 kDa fragment is responsible for the hydrophobic aggregation of brain G4 acetylcholinesterase - Fuentes_1988_Biochem.J_256_1047
Author(s) : Fuentes ME , Rosenberry TL , Inestrosa NC
Ref : Biochemical Journal , 256 :1047 , 1988
Abstract : Proteinase K treatment of the bovine brain acetylcholinesterase (AChE) releases a hydrophobic fragment of 13 kDa, which is entirely responsible for the aggregation of the G4 AChE in the absence of detergent. This observation provides evidence that the 13 kDa fragment, which comes from a previously identified 20 kDa subunit, is directly involved in the attachment of the G4 AChE to brain membranes. A model for the organization of the different sub-domains of the hydrophobic anchor of the G4 AChE is presented.
ESTHER : Fuentes_1988_Biochem.J_256_1047
PubMedSearch : Fuentes_1988_Biochem.J_256_1047
PubMedID: 3223943

Title : Axons grow in the aging rat but fast transport and acetylcholinesterase content remain unchanged - Inestrosa_1988_Brain.Res_441_331
Author(s) : Inestrosa NC , Alvarez J
Ref : Brain Research , 441 :331 , 1988
Abstract : Caliber and microtubular density of myelinated fibers, acetylcholinesterase (AChE) content and its accumulation at a ligature were studied in the phrenic nerve of mature (3-4 months) and aging (2-year-old) rats. The number of axons remained constant. The cross-sectional area of the nerve was 67% greater in the older group; the axoplasm, though, constituted about 20% of the nerve tissue irrespective of age. The mean cross-sectional area of myelinated axons was twice as big in aging compared to mature rats. All axons grew in the same proportion irrespective of their original caliber. The microtubular density of 3-microns axons was about 22 microtubules/micron2 in mature and aging rats. The AChE activity of aging rats was half as much as that of mature rats if it was expressed per wet weight of nerve tissue but did not change if it was expressed per nerve fiber. Twenty-four hours after ligation of the nerve, total AChE activity rose in mature and aging rats by ca. 168%; the molecular forms--asymmetric and globular--accumulated in the same proportion in both age groups. We conclude that myelinated axons grow in the adult stage of life but the structure of axoplasm, content of AChE per axon, and rate of fast transport remain lifelong features of nerve fibers.
ESTHER : Inestrosa_1988_Brain.Res_441_331
PubMedSearch : Inestrosa_1988_Brain.Res_441_331
PubMedID: 2451983

Title : A membrane-associated dimer of acetylcholinesterase from Xenopus skeletal muscle is solubilized by phosphatidylinositol-specific phospholipase C - Inestrosa_1988_Neurosci.Lett_90_186
Author(s) : Inestrosa NC , Fuentes ME , Anglister L , Futerman AH , Silman I
Ref : Neuroscience Letters , 90 :186 , 1988
Abstract : The susceptibility to phosphatidylinositol-specific phospholipase C of the membrane associated acetylcholinesterase (AChE) forms of Xenopus laevis skeletal muscle was examined. This treatment released almost all the detergent-soluble AChE species from muscle homogenates. Sucrose gradient analysis showed that the released acetylcholinesterase form corresponds to a hydrophilic G2 dimer, indicating that this dimer has a glycolipid anchoring domain which contains phosphatidylinositol.
ESTHER : Inestrosa_1988_Neurosci.Lett_90_186
PubMedSearch : Inestrosa_1988_Neurosci.Lett_90_186
PubMedID: 3412641

Title : Changes in contralateral synaptic acetylcholinesterase following motor nerve section in rats - Fadic_1988_Neurosci.Lett_90_229
Author(s) : Fadic R , Soza MA , Inestrosa NC
Ref : Neuroscience Letters , 90 :229 , 1988
Abstract : We report here that denervation of rat extensor digitorum longus, soleus and diaphragm muscle results in an increase of a subset of asymmetric acetylcholinesterase (class II A-forms) in the contralateral muscle, within a few days. This observation is interesting because it suggests a specific regulation of one asymmetric enzyme fraction, which is solubilized only in the presence of chelating agents and is thought to reside in the basal lamina.
ESTHER : Fadic_1988_Neurosci.Lett_90_229
PubMedSearch : Fadic_1988_Neurosci.Lett_90_229
PubMedID: 3412647

Title : Co-solubilization of asymmetric acetylcholinesterase and dermatan sulfate proteoglycan from the extracellular matrix of rat skeletal muscles - Brandan_1987_FEBS.Lett_213_159
Author(s) : Brandan E , Inestrosa NC
Ref : FEBS Letters , 213 :159 , 1987
Abstract : We have previously communicated that heparin released asymmetric acetylcholinesterase (AChE) from cholinergic synapses. Here we report studies showing that heparin, besides releasing asymmetric AChE from the skeletal muscle extracellular matrix (ECM), specifically solubilizes a dermatan sulfate proteoglycan (DSPG) which accounts for more than 95% of the 35S-released material. The co-solubilization of AChE and the proteoglycan opens up the possibility that both macromolecules could be involved in the formation of the soluble AChE complex observed after incubation of muscle homogenate with heparin. Our results suggest a possible association between asymmetric AChE and DSPG at the muscle ECM, moreover this work is the first report of the existence of DSPG at the skeletal muscle cell surface.
ESTHER : Brandan_1987_FEBS.Lett_213_159
PubMedSearch : Brandan_1987_FEBS.Lett_213_159
PubMedID: 3556575

Title : Acetylcholinesterase from bovine caudate nucleus is attached to membranes by a novel subunit distinct from those of acetylcholinesterases in other tissues - Inestrosa_1987_J.Biol.Chem_262_4441
Author(s) : Inestrosa NC , Roberts WL , Marshall TL , Rosenberry TL
Ref : Journal of Biological Chemistry , 262 :4441 , 1987
Abstract : Acetylcholinesterase extracted with Triton X-100 from bovine brain caudate nuclei was purified by affinity chromatography to apparent homogeneity. The purified enzyme was labeled with [3H]diisopropyl fluorophosphate at the active sites and with the photoactivated reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine, a compound which has been shown to be selective for the hydrophobic membrane-binding domains of several other proteins. The subunit structure was analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate before and after disulfide reduction. After reduction, a single 3H-labeled band at 70 kDa was stained by silver, but most of the 125I label corresponded to a 20-kDa species. Prior to reduction, five 3H-labeled and silver-stained bands were apparent at 70, 140, 160, 260, and greater than 360 kDa. These species were presumed to represent monomer and disulfide-linked oligomers of 70-kDa catalytic subunits. 125I label was selectively associated with the 160-, 260-, greater than 360-, and a 90-kDa species. Quantitative gel slicing of 3H- and 125I-labeled nonreduced enzyme supported a structural model in which the tetrameric enzyme is a dimer of nonidentical catalytic subunit dimers, one of which involves a direct intersubunit disulfide linkage between two 70-kDa catalytic subunit monomers and the second of which contains two disulfide linkages through an intervening 125I-labeled 20-kDa noncatalytic subunit. This 20-kDa subunit is proposed to contain the membrane attachment site. The brain enzyme did not contain components characteristic of the glycolipid anchors of erythrocyte acetylcholinesterases. However, part of the 125I label was associated with fatty acids, indicating that at least a portion of the brain enzyme membrane anchor is composed of nonamino acid components.
ESTHER : Inestrosa_1987_J.Biol.Chem_262_4441
PubMedSearch : Inestrosa_1987_J.Biol.Chem_262_4441
PubMedID: 3558347

Title : The synaptic form of acetylcholinesterase binds to cell-surface heparan sulfate proteoglycans - Brandan_1986_J.Neurosci.Res_15_185
Author(s) : Brandan E , Inestrosa NC
Ref : Journal of Neuroscience Research , 15 :185 , 1986
Abstract : We have previously communicated that heparan sulfate and heparin released 16S acetylcholinesterase (AChE) from cholinergic synapses. These experiments suggest that heparan-like molecules are involved in the anchorage of AChE to the neuromuscular junction. In order to prove the in vivo interaction between the 16S AChE and heparan sulfate residues, the binding of exogenously added 16S enzyme to intact cells rich in cell-surface heparan sulfate proteoglycans was examined; 16S AChE form was shown to bind to intact endothelial cells in a specific, time-dependent, saturable fashion. A single class of binding sites was involved and at saturation around 2.52 X 10(11) molecules of 16S AChE/cm2 were bound. Fifty percent of the binding of the 16S AChE was blocked by heparan sulfate, heparin, or previous treatment of the cell with heparitinase. The binding was reversed by exogenous heparin, but not by chondroitin sulfate or hyaluronic acid. Our results demonstrate that the synaptic form of AChE binds to heparan sulfate proteoglycans on the surface of the cell.
ESTHER : Brandan_1986_J.Neurosci.Res_15_185
PubMedSearch : Brandan_1986_J.Neurosci.Res_15_185
PubMedID: 2937928

Title : Atypical distribution of asymmetric acetylcholinesterase in mutant PC12 pheochromocytoma cells lacking a cell surface heparan sulfate proteoglycan - Inestrosa_1985_J.Neurochem_45_86
Author(s) : Inestrosa NC , Matthew WD , Reiness CG , Hall ZW , Reichardt LF
Ref : Journal of Neurochemistry , 45 :86 , 1985
Abstract : We studied the distribution of the molecular forms of acetylcholinesterase (AChE) in a stable variant (F3) of the rat pheochromocytoma cell line, PC12, that lacks a heparan sulfate proteoglycan on the cell surface. After treatment with nerve growth factor F3 cells synthesize less 4S enzyme, and more 10S and 16S enzyme than normal PC12 cells. This distribution is similar to that seen in normal cells after incubation with beta-D-xylosides, molecules that interfere with proteoglycan assembly. Using collagenase treatment and membrane-permeable and -impermeable inhibitors of AChE, we determined the cellular location of the AChE forms. Although in normal cells greater than 90% of the 16S AChE is on the cell surface, approximately 60% is present in an internal pool in the variant. Following irreversible inhibition of all forms of AChE in the variant, the newly synthesized 16S AChE appears in the internal pool after a 1-h lag, but is not detected on the cell surface until after 2.5 h. Our results thus show that 16S AChE is assembled internally within neuronal cells and that alterations in the synthesis and distribution of proteoglycans affect the total amount and cellular localization of the 16S AChE form.
ESTHER : Inestrosa_1985_J.Neurochem_45_86
PubMedSearch : Inestrosa_1985_J.Neurochem_45_86
PubMedID: 3158721

Title : Anchorage of collagen-tailed acetylcholinesterase to the extracellular matrix is mediated by heparan sulfate proteoglycans - Brandan_1985_J.Cell.Biol_101_985
Author(s) : Brandan E , Maldonado M , Garrido J , Inestrosa NC
Ref : Journal of Cell Biology , 101 :985 , 1985
Abstract : Heparan sulfate and heparin, two sulfated glycosaminoglycans (GAGs), extracted collagen-tailed acetylcholinesterase (AChE) from the extracellular matrix (ECM) of the electric organ of Discopyge tschudii. The effect of heparan sulfate and heparin was abolished by protamine; other GAGs could not extract the esterase. The solubilization of the asymmetric AChE apparently occurs through the formation of a soluble AChE-GAG complex of 30S. Heparitinase treatment but not chondroitinase ABC treatment of the ECM released asymmetric AChE forms. This provides direct evidence for the vivo interaction between asymmetric AChE and heparan sulfate residues of the ECM. Biochemical analysis of the electric organ ECM showed that sulfated GAGs bound to proteoglycans account for 5% of the total basal lamina. Approximately 20% of the total GAGs were susceptible to heparitinase or nitrous acid oxidation which degrades specifically heparan sulfates, and approximately 80% were susceptible to digestion with chondroitinase ABC, which degrades chondroitin-4 and -6 sulfates and dermatan sulfate. Our experiments provide evidence that asymmetric AChE and carbohydrate components of proteoglycans are associated in the ECM; they also indicate that a heparan sulfate proteoglycan is involved in the anchorage of the collagen-tailed AChE to the synaptic basal lamina.
ESTHER : Brandan_1985_J.Cell.Biol_101_985
PubMedSearch : Brandan_1985_J.Cell.Biol_101_985
PubMedID: 3161900

Title : Interaction of heparin with multimolecular aggregates of acetylcholinesterase - Torres_1985_Cell.Mol.Neurobiol_5_303
Author(s) : Torres JC , Inestrosa NC
Ref : Cellular Molecular Neurobiology , 5 :303 , 1985
Abstract : It has been reported previously that heparin, a sulfated glycosaminoglycan, releases the asymmetric 16 S form of acetylcholinesterase (AChE) from cholinergic synapses. Here it is shown that heparin releases the synaptic AChE not as individual 16 S species but as multimolecular aggregates (30 S) of such molecules. Heparin is able to convert low-ionic strength AChE aggregates into a heparin type of AChE aggregates. Our results suggest that the AChE aggregates detached by heparin are likely to be the physiologically important state of aggregation of the 16 S AChE form in the synaptic basal lamina.
ESTHER : Torres_1985_Cell.Mol.Neurobiol_5_303
PubMedSearch : Torres_1985_Cell.Mol.Neurobiol_5_303
PubMedID: 4064078

Title : Membrane-bound form of acetylcholinesterase activated during postnatal development of the rat somatosensory cortex - Inestrosa_1985_Dev.Neurosci_7_120
Author(s) : Inestrosa NC , Ruiz G
Ref : Developmental Neuroscience , 7 :120 , 1985
Abstract : We are interested in the expression of synapse-specific macromolecules and its correlation with the appearance of neuronal types and synaptogenesis during development of the mammalian brain. We report here studies showing that the appearance of acetylcholinesterase (AChE) at layer IV of the rat somatosensory cortex is correlated with the expression of a membrane-bound AChE. Both its electrophoretic mobility and its sedimentation coefficient remain unaltered during maturation; however, its kinetics parameters, the heat and fixative sensitivities and the substrate inhibition changed through development. Our results suggest that an adult form of membrane-bound AChE is expressed postnatally.
ESTHER : Inestrosa_1985_Dev.Neurosci_7_120
PubMedSearch : Inestrosa_1985_Dev.Neurosci_7_120
PubMedID: 2415318

Title : Binding of the asymmetric forms of acetylcholinesterase to heparin - Brandan_1984_Biochem.J_221_415
Author(s) : Brandan E , Inestrosa NC
Ref : Biochemical Journal , 221 :415 , 1984
Abstract : The interaction between acetylcholinesterase (EC 3.1.1.7) and heparin, a sulphated glycosaminoglycan, was studied by affinity chromatography. A specific binding of the asymmetric acetylcholinesterase to an agarose gel containing covalently bound heparin was demonstrated. This interaction required an intact collagenous tail, shown by the fact that the binding is abolished by pretreatment with collagenase. The globular forms did not bind to the column. Both total and intracellular asymmetric acetylcholinesterase forms isolated from the endplate region of the rat diaphragm muscle showed higher affinity for the heparin than did the enzyme from the non-endplate region. The binding to the resin was destabilized with 0.55 M-NaCl, and, among the various glycosaminoglycans tested, only heparin was able to displace the acetylcholinesterase bound to the column. Our results added further support to the concept that the asymmetric acetylcholinesterase forms are immobilized on the synaptic basal lamina via interactions with heparin-like molecules, probably related to heparan sulphate proteoglycans.
ESTHER : Brandan_1984_Biochem.J_221_415
PubMedSearch : Brandan_1984_Biochem.J_221_415
PubMedID: 6089739

Title : The electric organ of Discopyge tschudii: its innervated face and the biology of acetylcholinesterase - Mendez_1984_Cell.Mol.Neurobiol_4_125
Author(s) : Mendez B , Garrido J , Maldonado M , Jaksic FM , Inestrosa NC
Ref : Cellular Molecular Neurobiology , 4 :125 , 1984
Abstract : An ultrastructural, histochemical, and biochemical study of the electric organ of the South American Torpedinid ray, Discopyge tschudii, was carried out. Fine structural cytochemical localization of acetylcholinesterase (AChE) indicated that most of the esterase was associated with the basal lamina. Electron microscopy indicated no marked differences in the electrocyte ultrastructure between Discopyge and Torpedo californica. Discopyge electric organ possessed three molecular forms, two asymmetric forms (16 S and 13 S) and one globular hydrophobic form (6.5 S). The asymmetric 16 S AChE form was solubilized by heparin, a sulfated glycosaminoglycan, suggesting that heparin-like macromolecules are involved in the binding of the enzyme to the basal lamina. Our results show that cell-free translated AChE peptides, synthesized using Discopyge electric organ poly(A+) RNA, correspond to a main band of 62,000 daltons which probably represents the catalytic subunit of the asymmetric AChE.
ESTHER : Mendez_1984_Cell.Mol.Neurobiol_4_125
PubMedSearch : Mendez_1984_Cell.Mol.Neurobiol_4_125
PubMedID: 6488242

Title : Subcellular localization of acetylcholinesterase molecular forms in endplate regions of adult mammalian skeletal muscle - Fernandez_1984_Neurochem.Res_9_1211
Author(s) : Fernandez HL , Inestrosa NC , Stiles JR
Ref : Neurochemical Research , 9 :1211 , 1984
Abstract : The characterization of individual acetylcholinesterase (AChE) molecular form subcellular pools in adult mammalian skeletal muscle is a critical point when considering such questions as the origin, assembly, and neurotrophic regulation of these molecules. By correlating the results of differential extraction, in vitro collagenase digestion, and in situ pharmacologic probes of AChE molecular forms in endplate regions of adult rat anterior gracilis muscle, we have shown that: 1) 4.0S (G1) and 6.0S (G2) AChE are predominantly membrane-bound and intracellular; if an extracellular and/or soluble fraction of these forms exists, it cannot be adequately resolved by our methods; 2) 9-11S (globular) AChE activity is distributed between internal and external pools, as well as membrane-associated and soluble fractions; 3) 16.0S (A12) AChE is not an integral membrane protein and exists both intracellularly (25-30%) and extracellularly (70-75%).
ESTHER : Fernandez_1984_Neurochem.Res_9_1211
PubMedSearch : Fernandez_1984_Neurochem.Res_9_1211
PubMedID: 6504236

Title : 16S acetylcholinesterase of the extracellular matrix is assembled within mouse muscle cells in culture - Inestrosa_1984_Biochem.J_217_377
Author(s) : Inestrosa NC
Ref : Biochemical Journal , 217 :377 , 1984
Abstract : The present paper examines where the extracellular-matrix (ECM) 16S acetylcholinesterase (AChE, EC 3.1.1.7) is assembled in muscle cells in culture. The existence of an internal pool of 16S AChE was detected by using AChE inhibitors of differing membrane permeability. After irreversible inhibition of all cellular esterase, the newly synthesized 16S form appears in an intracellular compartment and is only later detected on the cell surface. Results show that the ECM 16S AChE is assembled within muscle cells.
ESTHER : Inestrosa_1984_Biochem.J_217_377
PubMedSearch : Inestrosa_1984_Biochem.J_217_377
PubMedID: 6696736

Title : Acetylcholinesterase is functional in embryonic rat muscle before its accumulation at the sites of nerve-muscle contact - Ziskind-Conhaim_1984_Dev.Biol_103_369
Author(s) : Ziskind-Conhaim L , Inestrosa NC , Hall ZW
Ref : Developmental Biology , 103 :369 , 1984
Abstract : We have examined the expression, the location, and the physiological activity of acetylcholinesterase (AChE) in developing intercostal muscles in the rat. Although focal accumulations of AChE at developing end plates do not appear until Embryonic Day (ED) 16-17, 16 S AChE is present at ED 14. Experiments with permeable and impermeable inhibitors established that prior to focal accumulation most of the 16 S enzyme is on the surface of muscle fibers, where it constitutes the major species. Intracellular recording from developing muscle fibers showed that as early as ED 14, AChE inhibitors prolonged evoked end-plate potentials. We conclude that prior to its focal accumulation, AChE is present on the surface of muscle fibers and is physiologically active. Histochemical staining of the focally accumulated enzyme demonstrated that the enzyme is concentrated both intracellularly and extracellularly at the sites of developing nerve-muscle contacts.
ESTHER : Ziskind-Conhaim_1984_Dev.Biol_103_369
PubMedSearch : Ziskind-Conhaim_1984_Dev.Biol_103_369
PubMedID: 6202574

Title : Age-related responses of skeletal muscle after ectopic innervation, with particular reference to 16S acetylcholinesterase, in adult rats - Maldonado_1984_J.Neurochem_43_375
Author(s) : Maldonado M , Ramirez BU , Ruiz G , Yamuy J , Inestrosa NC
Ref : Journal of Neurochemistry , 43 :375 , 1984
Abstract : The formation of ectopic junctions between the foreign fibular nerve and the soleus muscle of young (35-day-old) and mature (200-day-old) adult rats was induced by severing the normal nerve 4 weeks after implanting the foreign nerve. The various molecular forms of acetylcholinesterase (AChE) were studied both at the implanted region and at the original denervated endplates. The velocity of contraction was also studied. In young rats the 16S form was first detected in the ectopic junctions around day 5 after reinnervation; this form rapidly increased during the following weeks, reaching a plateau by day 20. By contrast, in mature rats the appearance of the 16S AChE was dramatically delayed; in fact, it could not be observed before day 80 after reinnervation. (The 16S AChE form appeared at day 20 after reinnervation in the original denervated endplates of young rats; however, at the same time, no effect was observed in mature animals.) The original, slow muscle fibers of the soleus became faster upon reinnervation; this change occurred also much earlier in younger than in mature rats. Our results indicate a loss of plasticity in the skeletal muscle of mature rats. We suggest caution in the use of the ectopic innervation model to study development in mature adult rats.
ESTHER : Maldonado_1984_J.Neurochem_43_375
PubMedSearch : Maldonado_1984_J.Neurochem_43_375
PubMedID: 6736957

Title : Heparin solubilizes asymmetric acetylcholinesterase from rat neuromuscular junction - Torres_1983_FEBS.Lett_154_265
Author(s) : Torres JC , Inestrosa NC
Ref : FEBS Letters , 154 :265 , 1983
Abstract : We are interested in the factors involved in the anchorage of acetylcholinesterase (AChE) to the synaptic basal lamina. Here, we report studies showing that heparin, a sulfated glycosaminoglycan, specifically solubilized AChE from endplate regions of rat diaphragm muscle. Of the several molecular forms of AChE present in that region, heparin only released the asymmetric A12 and A8 forms of the enzyme. Our results strongly support the involvement of heparin-like macromolecules in the in vivo immobilization of the collagen-tailed forms of AChE to the basal lamina of the neuromuscular junction.
ESTHER : Torres_1983_FEBS.Lett_154_265
PubMedSearch : Torres_1983_FEBS.Lett_154_265
PubMedID: 6832369

Title : Increase of muscle peroxisomal enzymes and myotonia induced by nafenopin, a hypolipidemic drug - Behrens_1983_Muscle.Nerve_6_154
Author(s) : Behrens MI , Soza MA , Inestrosa NC
Ref : Muscle & Nerve , 6 :154 , 1983
Abstract : The chronic administration of nafenopin, a hypolipidemic drug, induced an increase in catalase and acyl-CoA oxidase activities in various skeletal muscles, including the gracilis, diaphragm, soleus, and extensor digitorum longus. The magnitude of the increase was around 100% for both enzymes in each of the muscles studied in spite of the different basal level. These changes seem to be specific of the peroxisomal enzymes because acetylcholinesterase, which is not peroxisomal, did not follow the same pattern in all the muscles. Concomitant with the increase in muscle peroxisomal enzymes, the skeletal muscles presented an altered electromyogram with prolonged insertional activity, repetitive firing of action potentials, and myotonic runs characteristic of myotonia. Our results suggest a role for peroxisomes in the myotonic disorder.
ESTHER : Behrens_1983_Muscle.Nerve_6_154
PubMedSearch : Behrens_1983_Muscle.Nerve_6_154
PubMedID: 6855799

Title : Developmental regulation of 16S acetylcholinesterase and acetylcholine receptors in a mouse muscle cell line - Inestrosa_1983_Exp.Cell.Res_147_393
Author(s) : Inestrosa NC , Miller JB , Silberstein L , Ziskind-Conhaim L , Hall ZW
Ref : Experimental Cell Research , 147 :393 , 1983
Abstract : We have studied the appearance, distribution and regulation of acetylcholinesterase (AChE) and acetylcholine receptors (AChRs) in a mouse skeletal muscle cell line (C2), that was originally isolated and described by Yaffe & Saxel [54]. In culture, cells from this line form spontaneously contracting myotubes, with overshooting action potentials that are TTX-sensitive. After fusion of myoblasts into myotubes, there was a dramatic increase in the amount of both AChE and AChR. Three forms of AChE, distinguished by their sedimentation on sucrose gradients, were synthesized: 4-6S, 10S, and 16S. The 4-6S and 10S forms appeared 1 day after the cells began to fuse, whereas the 16S form appeared only 2 days after fusion began. Maximal levels of the 16S AChE form (25-30% of the total) were obtained by reducing the concentration of horse serum in the fusion medium. Prevention of myoblast fusion by reducing the calcium levels in the medium decreased the total AChE by 70%, and only the 4-6S form was synthesized. Blocking spontaneous contractile activity of the myotubes by tetrodotoxin (TTX) led to a 50% reduction in all three esterase forms. Thus, the 16S, or endplate form of AChE is not specifically regulated by electrical or contractile activity in the C2 cell line. After fusion the number of AChRs increased rapidly for 3-4 days and then stabilized. Receptor clusters, ranging from 10-30 micron in length, appeared 1 day after myoblast fusion began. When cells were grown in medium containing reduced Ca2+, the total number of AChRs was decreased by 20-50%. Reduction of Ca2+ after myotubes and AChR clusters had formed resulted in dispersal of AChR clusters. Inhibition of muscle contractions with TTX did not affect the number of AChRs or their distribution.
ESTHER : Inestrosa_1983_Exp.Cell.Res_147_393
PubMedSearch : Inestrosa_1983_Exp.Cell.Res_147_393
PubMedID: 6617773

Title : Neural 16S acetylcholinesterase is solubilized by heparin - Torres_1983_Biochem.J_215_201
Author(s) : Torres JC , Behrens MI , Inestrosa NC
Ref : Biochemical Journal , 215 :201 , 1983
Abstract : The effect of heparin, a sulphated glycosaminoglycan, on the solubilization of rat sciatic-nerve acetylcholinesterase (acetylcholine acetylhydrolase; AChE; EC 3.1.1.7) was studied. It was found that heparin solubilized esterase activity from ligated nerves. Sedimentation analysis revealed this activity to be mainly the 16S form. Chondroitin sulphate did not solubilize AChE activity, and protamine eliminated the solubilizing effect. Our results suggest the involvement of sulphated glycosaminoglycans in the intra-axonal localization and transport of 16S AChE.
ESTHER : Torres_1983_Biochem.J_215_201
PubMedSearch : Torres_1983_Biochem.J_215_201
PubMedID: 6626175

Title : The A12 acetylcholinesterase and polypeptide composition of electric organ basal lamina of Electrophorus and some Torpedinae fishes - Inestrosa_1983_Cell.Biochem.Func_1_41
Author(s) : Inestrosa NC , Mendez B
Ref : Cell Biochemistry & Function , 1 :41 , 1983
Abstract : Basal lamina (BL) of Torpedo, Discopyge and Electrophorus electric organs was purified in order to establish polypeptide composition and association with acetylcholinesterase (AChE). Results indicate that BL presents a distinct peptide pattern and that the A12 form of AChE is directly attached to it. Comparison of the species studied demonstrated similarities both in polypeptide composition and AChE content of the purified BL. Extractions of BL with solutions of high ionic strength, guanidine-HCl and acetic acid indicated the differential solubilization of various domains of BL polypeptides.
ESTHER : Inestrosa_1983_Cell.Biochem.Func_1_41
PubMedSearch : Inestrosa_1983_Cell.Biochem.Func_1_41
PubMedID: 6678617

Title : Association of the synaptic form of acetylcholinesterase with extracellular matrix in cultured mouse muscle cells - Inestrosa_1982_Cell_29_71
Author(s) : Inestrosa NC , Silberstein L , Hall ZW
Ref : Cell , 29 :71 , 1982
Abstract : Myotubes of a mouse muscle-cell line (C2) synthesize in culture a 16S form of acetylcholinesterase that is normally found only in regions of adult mouse muscle that contain endplates. The 16S enzyme in C2 cell extracts has the properties expected of acetylcholinesterase forms that have a collagen-like tail. In intact cells, the active site of the 16S acetylcholinesterase is protected by a membrane-impermeable inhibitor, and this form of the enzyme can be removed by treatment of the cells with collagenase. Thus the enzyme is extracellular. Its extraction by high ionic strength solutions lacking detergent suggests that the 16S form is associated with the extracellular matrix by ionic interactions. Histochemical staining shows focal patches of acetylcholinesterase activity on the cell surface. Collagenase treatment, which removes only the 16S form, abolishes this staining pattern, indicating that the patches consist of the 16S enzyme. We conclude that the 16S enzyme in C2 myotubes occurs in focal patches on the cell surface, where it is associated with the extracellular matrix.
ESTHER : Inestrosa_1982_Cell_29_71
PubMedSearch : Inestrosa_1982_Cell_29_71
PubMedID: 6286145

Title : Aneural muscle cell cultures make synaptic basal lamina components -
Author(s) : Silberstein L , Inestrosa NC , Hall ZW
Ref : Nature , 295 :143 , 1982
PubMedID: 7035963

Title : Acetylcholinesterase aggregates in a newly formed motor nerve-smooth muscle junction - Mendez_1981_Brain.Res.Bull_7_17
Author(s) : Mendez B , Inestrosa NC
Ref : Brain Research Bulletin , 7 :17 , 1981
Abstract : We have studied the changes in acetylcholinesterase (AChE) molecular forms during cross-innervation of the inferior smooth muscle of the cat nictitating membrane by the hypoglossal nerve. One month after functional cross-innervation AChE activity increases by two-fold above control values, and a new high molecular weight AChE form (A12) is detected, BW284c51, an anti-AChE, potentiates the contraction of the cross-innervated smooth muscle. Three months later, AChE activity has raised six-fold above normal values. At this time, half of the activity sediments to the bottom of the sucrose gradient and a time-dependent dissociation occurs in lighter AchE forms, reminiscent of AChE aggregates observed in the electric eel. We discuss the possibility that the multimolecular aggregates are involved in the immobilizatin of AChE at the neuromuscular junction of a motor nerve and a smooth muscle.
ESTHER : Mendez_1981_Brain.Res.Bull_7_17
PubMedSearch : Mendez_1981_Brain.Res.Bull_7_17
PubMedID: 7272784

Title : Cellular localization of the molecular forms of acetylcholinesterase in rat pheochromocytoma PC12 cells treated with nerve growth factor - Inestrosa_1981_J.Neurosci_1_1260
Author(s) : Inestrosa NC , Reiness CG , Reichardt LF , Hall ZW
Ref : Journal of Neuroscience , 1 :1260 , 1981
Abstract : In rat pheochromocytoma (PC12) cells treated with nerve growth factor (NGF), there are several molecular forms of the enzyme acetylcholinesterase (AChE) which sediment on sucrose density gradients at 4 to 6, 10, and 16 S, respectively. We have investigated the cellular localization of these forms in PC12 cells. In order to determine which forms are soluble and which are membrane bound, we extracted PC12 cells in buffers of various ionic strengths and detergent compositions. To distinguish internal from external forms of the enzyme, we examined the effect of di-isopropyl fluorophosphate and BW284c51 dibromide, membrane-permeable and -impermeable inhibitors of AChE, respectively, AChE forms in intact cells. We also determined the susceptibility of the forms in intact cells to collagenase treatment. Based on these studies, we conclude that the globular G1 and G2 (4 to 6 S) forms are internal and consist of both soluble and membrane-associated species. Thirty percent of the G4 (10 S) form is bound to cytoplasmic membrane structures, while the remainder occurs as an integral component of the plasma membrane. The asymmetric A12 (16 S) form is also a surface protein but is extracted by high salt without detergent and is released from intact cells by collagenase. This form thus contains a collagenous domain and is located outside of the plasma membrane, where it may be associated with an extracellular matrix.
ESTHER : Inestrosa_1981_J.Neurosci_1_1260
PubMedSearch : Inestrosa_1981_J.Neurosci_1_1260
PubMedID: 7310486

Title : Acetylcholinesterase like that of skeletal muscle in smooth muscle reinnervated by a motor nerve -
Author(s) : Inestrosa NC , Mendez B , Luco JV
Ref : Nature , 280 :504 , 1979
PubMedID: 460431

Title : Effects of denervation and of axoplasmic transport blockage on the in vitro release of muscle endplate acetylcholinesterase -
Author(s) : Inestrosa NC , Ramirez BU , Fernandez HL
Ref : Journal of Neurochemistry , 28 :941 , 1977
PubMedID: 68100

Title : Role of axoplasmic transport in neurotrophic regulation of muscle end plate acetylcholinesterase -
Author(s) : Ferdandez HL , Inestrosa NC
Ref : Nature , 262 :55 , 1976
PubMedID: 59316